Chapter 20: Atoms and Elements by KZvObXf4

VIEWS: 26 PAGES: 23

									AP Chemistry Notes – Chapter 2
   Chemistry Notes – Chapters 5 & 7

Atoms and Elements
What is sciences view on the cosmic origin of the elements that we
take for granted in our environment and lives?
   “Big Bang” Theory: (grapefruit sized sphere of matter exploded 15 billion years ago
        creating a cloud with a temperature of 1030 K, filled with protons, neutrons, and electrons. The
        cloud then cooled and the protons, neutrons and electrons began to form helium and hydrogen)
     The Sun:           After thousands of years it is believed that the hydrogen and helium condensed
        into stars like our sun. Each second in the sun 700 million tons of hydrogen is converted into 695
        million tons of helium and 3.9 x 1026 joules of energy. The mass that appeared lost was converted
        to pure energy (E = mc2).

                H                +                H                        He             +        Energy
                                                               Fusion
     Supernovas:             Exploding stars observed by us are called supernovas. Supernovas can be
        thought of as factories for heavier elements (elements larger than hydrogen and helium). It is
        thought the heavy elements produced from these supernovas move out through space and
        gradually condense into planets like Earth


2.1 Protons, Electrons, and Neutrons: Atomic Theory
A. Many of the experiments that have led to our current MODEL of the atoms involved:
1. Electricity (1700’s) – Benjamin Franklin
        o   Identified the existence positive (+) and (-) charges
        o   Opposite charges neutralize each other
        o   Like charges repel each other while unlike charges attract one another
2. Radioactivity (1899) – Henri Becquerel and Madame Curie
      o Uranium emitted rays that were named radioactivity, substances that emitted these rays are said to be
         radioactive.
      o Madame Curie isolated polonium and radium that emitted radioactivity
                                         Positively Charged Plate
                                                  +
                Radioactive                                                          Detector
                Source                                                               Plate (Film)
                                                  -
                                         Negatively Charged Plate

Alpha Radiation (α) - Large massed particles, charged with a +2 charge
Beta Radiation (β) - Small massed particles, with a –1 charge
Gamma Radiation (γ) - No charge or mass

                                                                                                             1
B. The Nuclear Model of the Atom
 All matter is made up of tiny particles called atoms
 An atom is more than 1 000 000X smaller than the thickness of a single hair on your head.
 Atoms have the same basic parts

                   Most of the Mass                   Atom                        Most of the space


                      Nucleus                                                         Electron
                                                                                       Cloud

                      (nucleons)
       Neutrons                       Protons                      =                Electrons

       Uncharged                Positively Charged                                Negatively Charged
       Particles                     Particles                                        Particles




                                                      Electrically Neutral


C. Experiments Leading to “NUCLEAR MODEL” of the Atom

Scientist             Description                                      Name of Experiment              Outcome
John Dalton           Dalton’s Atomic Theory (model)                  Dalton’s Atomic Theory
(1780’s)              *1) All elements are composed of tiny
                          indivisible particles called atoms
                      *2) Atoms of the same element are identical.
                          Atoms of any one element are different from
                          any other element.
                       3) Atoms of different elements can physically
                          MIX together OR can CHEMICALLY COMBINE
                          with one another in whole-number ratios to
                          make compounds.




                       4) Chemical reactions occur when atoms separated,
                         joined or rearranged. Atoms of one element are
                          never changed into atoms of another element as
                          a result of a chemical reaction

                      *Later proved wrong by other observations and experiments
                                                                                                                 2
JJ Thompson             A beam of electrons (cathode rays)       Cathode Ray Experiment     *electrons
(1876)                  passes through an electric and                                      discovered
                        magnetic field and were deflected                                   *charge to
                        away from the negative plate                                        mass ratio
                                                                                            electrons

Thompson’s Cathode Ray Experiment




Eugene Goldstein        A beam of protons (canal rays)           Canal Ray Experiment       *protons
(1876)                  passes through an electric and                                      discovered
                        magnetic field and were deflected
                        away from the positive plate

Robert Millikan         Oil drops that had electrons             Oil Drop Experiment         * Mass of
(1912)                  adhered to them fell between two                                     an electron
                        charged plates, by adjusting charge                                  9.11 x 10-28g
                        an the plates and by using Thompson’s                                *Charge of
                        charge to mass ratio he determined the                               an electron
                        mass and charge of an electron                                    -1.60 x 10-19 C

Millikan’s Oil Drop Experiment




                                                                                                             3
Ernest Rutherford      A beam of positive alpha (α) was directed    Gold Foil Experiment   *nucleus
                       at a piece of thin gold foil. A screen was                          discovered
                       was used to detect particles passing
                       through. Most alpha particles passed
                       through but some were deflected from
                       their path (even backwards) by the
                       dense, positively charged nucleus of
                       some of the gold atoms.

Rutherford’s Gold Foil Experiment




Where did all these experiments on the atom leave us???????

NUCLEAR MODEL of the Atom:




                                                                                                        4
Review
The following scientists and the research that they carried out was pivotal in creating the Nuclear Model (Theory)
of the atom. Please match the experiment and finding on the left with scientist on the right :
______ a) Oil Drop Experiment; Using charge/mass ratio from cathode
           ray studies the mass and charge of an electron was determined            a) Eugene Goldstein
______ b) Gold Foil Experiment; Alpha particles directed at a piece of gold
          foil were deflected supporting the existence of a dense positively        b) Robert Millikan
          charged nucleus.
______ c) Canal Ray Experiment; Bema of proton rays (canal rays) were passed        c) JJ Thompson
           through an electric field and were deflected away from the positive
            plate supporting the existence of protons                               d) Ernest Rutherford
______ d) Cathode Ray Experiment; A beam of electrons were passed
           through an electric field and were deflected away from the negative
            plate supporting the existence of electrons



2.2 Atomic Number and Atomic Mass
A. Atomic Number (Z)


The number of protons in the nucleus of an atom of an element is its atomic number, given the symbol Z.

   All atoms of the same element have the same number of protons in the nucleus.
   Atoms of an element have the same number of protons as electrons making them ___________________.
   Chemical properties (how atoms react) of an element depends on the number of electrons in its atoms.
   The identity of an atom can be determined from the number of the protons in the nucleus.
   Hydrogen is the simplest element, its atoms only have one proton in their nucleus
                                                                                              29
   The number of protons in an atom of any element can be found on the periodic table:

                                                          Atomic Number (Z)                 Cu
                                                                                          63.546
Practice:
a) How many protons in an atom of uranium?_________
b) Atoms are neutral (have no net charge), knowing this how many electrons do you think a uranium atom
would have?___________
c) What type of element has atoms that contain 20 protons?                  __________________
d) What type of element has atoms who electron clouds contain 7 electrons? __________________



B. Relative Atomic Mass and the Atomic Mass Unit
What is the mass of an atom of an element?
 Masses of atoms are always determined RELATIVE to the carbon atom that is made up of 6 protons,
   6 neutrons, and 6 electrons. This carbon atom has been assigned a mass of EXACTLY 12.000
   atomic mass units (amu).
 One atomic mass unit, 1 amu, is 1/12th the mass of carbon atom that is made up of 6 protons, 6
   neutrons, and 6 electrons.
 The “amu” can be related to the gram by the following conversion factor: 1 amu = 1.661 x 10-24 g

                                                                                                                 5
For example:
An oxygen atom has been found to be 1.33X the mass of a carbon atom with 6 protons, 6 neutrons and 6
electrons (12.00 amu). What is its mass in amu’s? grams?




C. Mass Number (A)



                             Mass
Particl e    Grams                  Relative Mass (amu)       Charge       Symbol
Electron     9.109 x 10-28          0.00549                     -1         e1-
*Proton      1.673 x 10-24          1.01                        +1         p1+
*Neutron     1.675 x 10-24          1.01                         0         n0

*Protons and neutrons have masses very close to 1 amu

The sum of the number of protons and neutrons for an atom is called its mass number and is given the
symbol A.




                                                    Determine the mass of ONE Atom in amu and g’s




                                                                                                       6
Examples:
1) A sodium atom has 11 protons and 12 neutrons in its nucleus what is its:
mass number (A) ?_____ atomic number (Z)?______ How many electrons would it have?________

2) An atom is made up of 16 protons, 16 neutrons, and 16 electrons. Using your periodic table what is the
identity of the element (Symbol)?_________ Mass number (A)?_______ Atomic number (Z)?_______

3) a) Identify the following atoms…




                 ______________                  17 e-            ________________




b) Why is the electron cloud of the atom with 17 e1- larger than the atom with 10 e1-?

3) Complete the table assuming all species are atoms:
Name         Symbol        Atomic         Composition of Nucleus (nucleons)   Mass       Number of
                           Number            Protons          Neutrons        Number     Electrons
                            (Z)                                                (A)

Iron          ________      _______       ___________       ___________           56     _________

_________ ________            80          ___________            120          _______ _________

_________ ________          _______            47           ___________       _______         47

_________        Pb         _______       ___________       ___________           207    _________

_________ ________          _______       ___________             31              59     _________



C. Symbolizing Atoms of Various Elements

Atoms of various elements can be symbolized using    X NOTATION or HYPHEN NOTATION:


       X NOTATION                                              HYPHEN NOTATION
Mass Number                 A
      Symbol                 X                                 Element Name – Mass#
Atomic number               Z

Example : The most common atom of uranium has 92 protons, 146 neutrons and _______electrons.
Symbolize this atom using both techniques described above:



                                                                                                        7
Practice:
a) What is the mass number of a calcium atom with 24 neutrons? Symbolize using both methods?



b) Identify the element who’s atoms are identified…
i.) with the following symbol     31
                                     ??                        _________________________
                                  15

ii) as having 13 electrons and a mass number of 27             _________________________
iii) as having (Z) = 19 and (A) = 39.                          _________________________

c) What is the identity of an element whos atoms have 90 protons and 142 electrons? Symbolize using
both methods?




d) Complete the table:

X-NOTATION    HYPHEN NOTATION             Protons      Neutrons      Electrons Atomic # Mass #
                                                                                 (Z)     (A)

80
     ??       ___________________ _______              ________      ________ ______ _______
35

________             Sulfur-32           _______       ________      ________ ______ _______


                                            2.3 Isotopes
                                            Only in VERY few instances (for example, aluminum,
                                            fluorine, and phosphorous) do all atoms of the same
                                            element have the same mass. Most elements consist of
                                            atoms having different mass numbers. Atoms with the same
                                            atomic number (number of protons) but different mass
                                            numbers (different number of neutrons) are called
                                   ??
                                            isotopes.
                                                                Sample of Neon Atoms




                ??
                ??




                                            Symbol
                                            Notation _____________   _______________   ______________
                                                                                                        8
Identifying and Quantifying Isotopes of an Element – The Mass Spectrometer
 The mass number of an isotope is an approximation of the exact atomic mass of the isotope.
 The masses of isotopes of an element and their percent abundance experimentally determined
   using a MASS SPECTROMETER.

The mass spectrometer is an analytical instrument used to measure atomic masses (mass of atoms) and molecular
masses (masses of molecules) directly.




A. Isotope Abundance
                                                    Isotope        Mass          Relative   Percent
                                                                   (amu)         Abundance Abundance



                                                    ______         19.9924       ________       ________



                                                    ______         20.9940       ________       ________



                                                    ______         21.9914       ________       ________




               Important points regarding exact atomic masses:
           o   The exact mass of any isotope of an element is not an integral (whole) number (except
               for carbon-12, which is EXACTLY 12.000 by definition).
           o   The exact mass of any atom is slightly less than the sum of the masses of protons,
               neutrons, and electrons in the atom. This difference is sometimes called the mass defect,
               and is related to the mass that was converted to energy (E = mc2) to bind the particles
               found in the nucleus (protons and neutrons) together.

                                                                                                                9
B. Using Mass Spectrometer Data to Calculate the Atomic Weight of an Element
The atomic weight an atom of an element must be somewhere between the exact atomic masses of each
isotope. The atomic weight of an element is a weighted average of the exact masses of each
isotope of an element. This is why atomic weights are NEVER whole numbers.

Atomic =(relative abundance Isotope 1)(Exact Mass Isotope 1) + (relative abundance Isotope 2)(Exact Mass Isotope 2). . .
Weight




Practice:
1. If you could count out 10,000 boron atoms from a natural sample 1991 of them would be boron-10 and
8009 of them would be boron-11 atoms. The percent of a certain isotope in a sample of a naturally
occurring element is termed percent abundance.

                             RELATIVE ABUNDANCE                     X 100% = PERCENT ABUNDANCE

Percent Abundance = number of atoms of a given isotope              X 100% =
                     total number of atoms sampled



a. Calculate the abundance of each isotope of Boron:
                                                Isotope Relative Mass               Relative           Percent
                                                                                    Abundance          Abundance
                                        11
                           8009           B     or      Boron-11   11.0093 amu     ___________        ____________
Boron    10 000 Boron atoms             5
Sample
                           1991         10
                                          B     or      Boron-10   10.0129 amu     ___________        ____________
                                        5
                                                                        Total      ___________        ____________


b. Calculate the weighted average atomic mass of Boron:




                                                                                                                     10
2. a) Argon has three isotopes with 18, 20, and 22 neutrons, respectively. What are the mass numbers
and symbols of these three isotopes?




b) Gallium has two isotopes: Gallium-69 and Gallium-71.
i) How many protons and neutrons are in the nuclei of each isotope?
                      Protons      Neutrons
Gallium-69            _______      _______
Gallium-71            _______      _______

ii) If the abundance of Gallium-69 is 60.1%, what is the abundance of Gallium-71?_____




Mass Defect Problem (E = mc2)
You might expect the mass of a deuterium (2H), would be the sum of the masses of one proton and one
neutron
Mass of proton      +     Mass neutron          =     Mass Deuterium Atom
1.007276 amu              1.008665                    2.015941

However the actual mass of 2H (which is actually measured to be 2.01355 amu using a mass
spectrometer) is LESS than the some of its constituents. Where did the mass disappear to?

=      Actual mass of Deuterium   -      Theoretical mass of Deuterium
=
=      ________________amu

The”missing mass” is converted to energy, the binding energy (E= mc2)



2.4 Atomic Weight (Mass) of Elements
   The mass shown on the periodic table is the weighted average of the exact masses of each isotope
    of an element
                                                                                  29
                                                                                  Cu
                                                                                 63.546


   The mass shown on the periodic table when rounded is indicative of the most abundant isotope of an
    element.
   ISOTOPES OF THE SAME ELEMENT CHEMICALLY REACT IDENTICALLY.



                                                                                                       11
Practice Calculating the Atomic Weight of an Element:
Using the percent abundance and atomic masses of each of nitrogen’s isotopes given on page 8 of this
packet of notes, calculate the average atomic mass of nitrogen.




Calculating the Abundances of an Isotope
The element europium exists in nature as two isotopes: europium-151 which has a mass of 150.9196 amu
and europium-153 which has a mass of 152.9209. The weighted average atomic mass of europium is
151.96 amu. Calculate the relative abundance of each isotope of europium
Element       Symbol       Atomic Weight        Mass Number          Isotopic Mass       Abundance
                           (weighted avg)                              (amu)
Europium       Eu            151.96             151                  150.9196            _______%
                                                153                  152.9209            _______%




                                                                                                       12
Practice Calculating the Abundance of Isotopes of an Element:
1) Using the data from page 7 of this packet of notes, calculate the abundances of each of the two
isotopes of chlorine.




2) Thallium has two stable isotopes, 203Tl and 205Tl. What is the weighted average atomic weight of
thallium? Which isotope is more abundant? Explain




2.5 Atoms and the Mole (Counting by Weighing)
In chemistry we need a method of counting atoms, no matter how small they are. We must be able to
connect the macroscopic world (what we can see) with the microscopic world of atoms, molecules and
ions. We do this by defining a convenient unit of matter that contains a known number of particles. The
chemical counting quantity is the mole (mol). The mole is the SI base unit for measuring the amount of
a substance.


A mole is the amount of a substance that contains as many elementary entities (atoms, molecules, or
anything else) as there are atoms in exactly 12 g of the carbon-12 isotope



In 12.0 g of carbon-12 atoms there are 6.02 x 1023 atoms (this is Avogadro’s Number)

1
2.0 g carbon-12 atoms   = 6.02 x 1023 carbon atoms      = 1 mole

                                                               Avogadro’s Number
The Molar Mass
The mass in grams of one mole of atoms of any element (6.02 x 1023 atoms of that element) is the molar
mass of that element. The units for the molar mass of an element are grams/mole. For elements,
molar mass is an amount in grams numerically equal to the atomic mass in atomic mass units. This value is
most easily found on the periodic table:


                                                                                                       13
Counting ATOMS By Weighing


Molar mass of copper (Cu) =        mass of exactly mol of Cu atoms               29
                            =      63.546 g/mol                                  Cu
                            =      mass of 6.02 x 1023 Cu atoms                  63.546



In other words…             1 mole Cu    =   6.02 x 1023 atoms of Cu   = 63.546 g Cu

Practice:
1) a) What is the mass, in grams, of 1.5 mol of copper?




b) If a copper ornament has a mass of 2.0 g, how many copper atoms are in the ornament?




c) If a copper ornament has a mass of 2.0 g, how many moles of copper atoms are in the ornament?




d) What is the mass of a single atom of copper?




                                                                                                   14
Homework
2) i) A lead fishing weight has a mass of ______g,


Conversion Table:    1 mole Pb atoms   =    ______________g Pb a         =    6.02 x 1023 atoms of Pb
a) How many moles of lead atoms are present?           b) How many lead atoms are present?




c) What is the mass of one atom of lead in grams?




3) The mass of a single piece of pencil graphite (pure carbon) is ____________g.

Conversion Table:    1 mole C atoms    =    ______________g C        =       6.02 x 1023 atoms of C


a) How many moles of carbon atoms are present?       b) How many carbon atoms are present?




c) If you wanted 6.5 x 1013 carbon atoms, how many grams of carbon would you need to mass out?
d) If you wanted 6.5 x 1013 carbon atoms, how many moles of carbon atoms would you need?




4) The mass of Mr. B’s gold ring (Au) is ____________g.

Conversion Table:    1 mole Au atoms   =     ______________g Au          = 6.02 x 1023 atoms of Au

a) How many moles of gold atoms are present?     b) How many moles of gold atoms are present?




                                                                                                        15
b) a) A single atom of this element has a mass of 2.28 x 10-22 g. What is its molar mass and identify the
element? (Hint: Remember the units for molar mass are g / mol)




c) To what group and period does the element in part a belong? Group_________Period_________




6) A 5.00 g sample of an unknown element is known to contain 0.2632 moles of atoms. What is the
identity of the unknown element (Hint: Remember the units for molar mass are g / mol)? What state of
matter is this element present in at room temperature?




7) a) Which has more atoms present 1 mole of Copper (Cu) or 1 mole of Carbon (C)? Explain




b) Which has a greater mass 1 mole of Copper (Cu) or 1 mole of Carbon (C)? Explain




c) Which contains more atoms 6.0 g of carbon or 10 g of neon? Explain




                                                                                                        16
2.6 The Periodic Table
The most useful tool in chemistry is the ___________________ ___________________.
Some of the things we can get from it…
State of matter at room temperature:      Solid (Black), Liquid (Blue), Gaseous (RED)
Diatomic Elements (there are 7):          H2, N2, O2, F2, Cl2, Br2, I2
Information on Each of the elements:
                                                     29                        ________________

                                               Cu                          _________________
                                              63.546                       _________________
A. Features of the Periodic Table                                          ______________
                                                                           ______________




Main Features of the Table
 Elements with similar chemical and physical properties lie in VERTICAL columns called _______ or
   ___________. The periodic table is made up of _______ groups. In the United States we see
   them numbered 1A-8A and 1B-8B. Typically they are numbered 1-18.
 Groups 1-2 and 13-18 are called main group elements while the groups 3-12 are called transition
   elements.
 There are ______ horizontal rows in the periodic table, these are called ______________
 Inner transition elements (Lanthanides and Actinides)
                                                                                                  17
Element                     Period         Group (Family)        Main Group or Transition
Silver (Ag)                 _____          ___________           ___________________
Calcium (Ca)                _____          ___________           ___________________
Iodine (I)                  _____          ___________           ___________________
_________________             7                  2               ___________________
_________________             2                  17              ___________________

Periodic Table Divided According to Element Properties

Metals
Properties: Metals are…
Solid at room temperature (except for mercury), conduct
electricity, ductile, malleable, form alloys (brass is a
homogeneous mixture of copper and zinc atoms), high luster
(shiny). Metals lie to the _____________________ of
the “staircase.”
**When reacting with non-metals atoms, metal atoms
tend to __________electrons to become stable forming
POSITIVELY charged atoms (______________).


Non-Metals
Properties: Non-Metals are…
Solid in some cases (ie. sulfur), liquid in some cases (ie. bromine), and gaseous in other cases (oxygen),
don’t conduct electricity. Nonmetals lie to the _____________________ of the “staircase.”
**When reacting with metals atoms, non-metal atoms tend to __________electrons to become
stable forming NEGATIVELY charged atoms (________________).


Metalloids (Semimetals):
Properties: Semimetals are…
elements that have characteristics of metals and non-metals. Nonmetals lie on the “staircase.”


B, Si, Ge, As, Sb, & Te

The Development of the Periodic Table

Mendeleev (Father of the Periodic Table)
The first periodic table of the elements created by Dmitri Mendeleev was arranged based on atomic
masses. Upon studying the chemical and physical properties of the elements known at his time (1869)
he realized elements with similar properties appeared in a regular pattern (periodicity). He organized
the elements into a table by lining them up in a horizontal row in order of increasing atomic mass.
Every time he came to an element similar to one already in the row, he started a new row. The columns
then contained elements with similar chemical and physical properties.

                                                                                                             18
Moseley
In 1913, H.G.J Moseley REORDERED the table so that elements were organized into a table by
increasing atomic number. The law of chemical periodicity is now stated as “ the properties of the
elements are periodic functions of their _______________________________.


2.7 An Overview of the Elements




The groups of the periodic table have similar chemical and physical properties, and several of these
groups have distinct names that are important to know:



Group 1A (1) – The Alkali Metals
All elements are metals and solids at room
temperature. All metals in this group are VERY
reactive this means in nature you find these
elements in compounds. These elements react
with water to produce alkaline (basic) solutions.

Group 2A (2) – The Alkaline Earth Metals
All elements are metals and solids at room
temperature. All metals in this group are VERY
reactive this means in nature you find these
elements in compoundsThese elements (Except
Beryllium) react with water to produce alkaline
(basic) solutions.




                                                                                                       19
                                     Groups 1B-8B Transition Metals
                                     All elements in this portion of the periodic table are metals
                                     Virtually all transition metals have commercial uses.

                                     Commercial Uses of Transition Metals:
                                     Structural Material:             Iron (Fe), Titanium (Ti),
                                     Paints:                          Chromium (Cr), Copper (Cu)
                                                                      Titanium (Ti), Chromium (Cr)
                                     Catalytic Converters:            Platinum (Pl)
                                     Coins:                           Copper (Cu), Nickel (Ni), Zinc (Zn)
                                     Nuclear Power Plants :           Uranium-235 (235U)

                                     Biological Roles of Transition Metals:
                                     Red Blood Cell –Iron (Fe) is found in the ___________ carrying
                                     component of our blood (hemoglobin).


Group 3A (13)- Boron Group (Family)
Al, Ga, In, and Tl are all metals whereas Boron (B) is a metalloid
Aluminum (Al) is the most abundant metal in the earth’s crust

Group 4A (14) – Carbon Group (Family)
Starting in this group, groups will begin to contain more and more non-metals.
Nonmetals: Carbon Metalloids: Silicon, Germanium          Metals: Tin, Lead
Carbon is the basis for the great variety of compounds that make-up living things.
Carbon can exist in several distinct forms                Graphite
each with their own distinct set of                       Diamond
chemical and physical properties
Bucky Ball Carbon                                         Buckminsterfullerene (BuckyBall Carbon)




Allotropes- Distinct forms of an element with their own unique physical and chemical properties

Group 5A (15) – Nitrogen Group (Family)
Nitrogen (N2) is the most abundant element in the Earth’s atmosphere. Nitrogen is also a critical
element found in chlorophyll, proteins, and DNA.

Phosphorous is essential to life as a constituent in bones and teeth.

                                                                                                       20
Group 6A (16) – Oxygen Family
Oxygen (O2) is the second most abundant element in the Earth’s atmosphere. Most of the energy that
powers life on Earth is derived from reactions in which oxygen combines with other substances.
Example:
Burning Gasoline (Octane):

C8H18 (l) +         O2 (g)               CO2 (g)     +       H2O (g)
Oxygen is the most abundant element in the Earth’s crust and in the human body

Oxygen also has allotropes: ____________________ and ____________________


Group 7A (17) – Halogens
All elements in this group are NON-METALS
This group contains the most reactive of all
NON-METAL elements
All elements in this group are diatomic elements
(F2, Cl2, Br2, and I2)
All react VIOLENTLY with alkali metals (also
with other metals just not as violently)




Group 8A (18) – Noble Gases
All elements in this group are NON-METALS
This group contains the least reactive of all NON-METAL elements




                                                                                                     21
               Elemental Make-up: Human Body


                         2.1
                    1.9
                  3.1
        10.0
                                                   Oxygen
                                                   Carbon
                                                   Hydrogen
                                                   Nitrogen
18.1                                               Calcium
                                         64.8      Other




               Elemental Make-up: Earth's Crust




                  4.8     3.4
         7.6
                                                   Oxygen
  7.9
                                           49.8    Silicon
                                                   Other
                                                   Aluminum
                                                   Iron
                                                   Calcium
        26.5




         Elemental Make-up: Earth's Atmosphere




                   7.6
         7.9
                                                  Nitrogen
                                                  Oxygen
                                                  Carbon Dioxide
                                         49.8     Argon and Others
 26.5




                                                                     22
Periodic Table Practice Problems :
1) Identify a Noble Gas with 54 protons in the nucleus                                   ________

2) In what period(s) do we find a solid, liquid, and a gas element (at lab conditions)   ________

3) In what group(s) do we find a solid, liquid, and a gas element (at lab conditions)    ________

4) Identify a transition element with 42 electrons                                       ________

5) How many elements are found in …
a) Period 2                                                                              ________
b) Period 4                                                                              ________
c) Group 15                                                                              ________


6) In what group do we find 1 non-metal, 2 metalloid, and 3 metal elements               ________


7) In what group do we find the most chemically reactive:
a) Metals                                                                                ________
b) Non-metals                                                                            ________


8) Which of the Noble gases has ONLY radioactive isotopes                                ________


9) This group containing only non-metals is made up of only monatomic gaseous
elements                                                                                 ________


10) A radioactive element whose atoms contain 95 protons and 95 electrons
that are commonly used in household smoke detectors.                                     ________


11) A inner transition (actinide series) element whose atoms contain 90 protons
and 95 electrons that are commonly used treat lantern mantles to increase the
amount of light given off when they burn (this element is also radioactive)              ________


12) The most reactive of all NON METAL elements                                          ________

13) The most reactive of all METAL elements                                              ________

14) What element has a molar mass that is ½ the molar mass of manganese (Mn)             ________

15) Identify the element with the following symbol        39
                                                               ??                        ________
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16) An alkaline earth metal element that is important to healthy bones                   ________

17) A diatomic element found in group 17 period 5                                        ________

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