Atoms_ Elements_ and Ions

Document Sample
Atoms_ Elements_ and Ions Powered By Docstoc
					Elements &
  Atoms

 with Mr.
 Khatter
                   Elements
The purest form of something – so
pure that there’s NOTHING you
can do to it to separate it into
something else.
 Left to right: pure forms of the metals Cobalt, Iron, and Nickel
• An _____ is the smallest particle of
  an element that has the chemical
  properties of the element.



                                    Copper
                                    atoms on
                                    silica
                                    surface.
           The Atom
An atom consists of a
• nucleus
   –(of protons and neutrons)
• electrons in space about the nucleus.


                          Electron cloud

                            Nucleus
     Atoms
All matter is composed of
      small, fast moving
   particles called atoms.
    These atoms can join
       together to form
          molecules.
     This theory is really
  thousands of individual
    theories that provide
   evidence for the whole
            theory.
           Atoms
  Since the atom is
too small to be seen
even with the most
      powerful
    microscopes,
scientists rely upon     Believe it or not this is a
                       microscope. Even with the
models to help us to   world’s best microscopes we
                          cannot clearly see the
   understand the      structure or behavior of the
                                   atom.
        atom.
   Scientific Models
    Scientists create
 models to help them
 to visualize complex
properties, structures
  or behaviors. Since
 the atom is so small,
scientists must gather
  indirect evidence to
develop their models.       This is a model of a very
                           complex molecule made of
                         many different kinds of atoms.
                         Each colored ball represents an
                          atom of a different element.
Is this really an Atom?

            This model (left)
             represents the
              most modern
             version of the
                 atom.
            (Artist drawing)
ATOM
COMPOSITION
 The atom is mostly
 empty space
•protons and neutrons in
      the nucleus.
•the number of electrons is equal to the
number of protons.
•electrons in space around the nucleus.
•extremely small. One teaspoon of water has
3 times as many atoms as the Atlantic Ocean
has teaspoons of water.
  ATOMIC COMPOSITION
• Protons (p+)
  – + electrical charge
  – mass = 1.672623 x 10-24 g
  – relative mass = 1.007 atomic
    mass units (amu) but we can round to 1
• Electrons (e-)
  – negative electrical charge
  – relative mass = 0.0005 amu
                       but we can round to 0
• Neutrons (no)
  – no electrical charge
  – mass = 1.009 amu but we can round to 1
    Atomic Number
All atoms of the same element
 have the same number of
 protons in the nucleus

    13       Atomic number
     Al     Atom symbol
   26.981    AVERAGE Atomic Mass
         Mass Number
• C atom with 6 protons and 6 neutrons
  is the mass standard
• = 12 atomic mass units
• Mass Number
     = # protons + # neutrons
• NOT on the periodic table…(it is the
  AVERAGE atomic mass on the table)
• A boron atom can have
     5 p + 5 n = 10 amu
             Isotopes
• Atoms of the same element but
  different mass number.
• Boron-10 (10B) has 5 p and 5 n
• Boron-11 (11B) has 5 p and 6 n
                      11B




               10B
Two isotopes of sodium
Isotopes &
Their Uses
Bone scans with
radioactive
technetium-99.
  Isotopes & Their Uses




The tritium content of ground water is
used to discover the source of the water,
for example, in municipal water or the in
the steam from a volcano.
         Atomic Symbols
 Show the name of the element, a hyphen, and
 the mass number in hyphen notation

                 sodium-23

 Show the mass number and atomic number
 in nuclear symbol form
 mass number
                       23 Na

 atomic number         11
                Isotopes
Which of the following pairs
 represent isotopes of the same
 element?

234       234        235       238
      X         X          X         X
92        93         92        92
          Learning Check – Counting


 Naturally occurring carbon consists of three
 isotopes, 12C, 13C, and 14C. State the number of
 protons, neutrons, and electrons in each of
 these carbon atoms.
    12C             13C              14C
     6               6               6


#p+ _______       _______           _______
#no _______       _______           _______
#e- _______        _______          _______
            Answers

    12C      13C      14C
        6    6        6


#p+ 6        6        6

#no 6        7        8

#e- 6        6        6
                Learning Check

An atom has 14 protons and 20 neutrons.
  A. Its atomic number is
     1) 14           2) 16            3) 34
  B. Its mass number is
     1) 14            2) 16             3) 34

  C. Another isotope of this element is
     1) 34X           2) 34X            3) 36X
       16                14               14
Elements &
  Atoms
  with Mr.
 Khatter…
The journey
 continues
AVERAGE                         11B


ATOMIC
                          10B
MASS

 • The atomic mass an atom is usually
   listed underneath the atom’s
   alphabetical symbol on the periodic
   table.
 • The atomic mass is an average of
   the masses of the atom in its
   various forms (isotopes).
AVERAGE                                11B


ATOMIC
                                 10B
MASS

 • Boron exists in its balanced form with 5
   protons and 5 neutrons only 20% of the time
   (as far as we’ve found it in nature so far).
 • In other words, 20% of the time we have found
   Boron, it has had an atomic mass of 10.
 • The other 80% of the time it has an atomic
   mass of 11, meaning that it has 5 protons and
   6 neutrons.
AVERAGE                              11B


ATOMIC
                             10B
MASS

 • By knowing that Boron exists with an
   atomic mass of 10 (5p + 5n) 20% of the
   time and with an atomic mass of 11 (6p +
   5n) 80% of the time, scientists created
   the following formula to find Boron’s
   average atomic mass of 10.811.

           (20% x 10) + (80% x 11)
AVERAGE
ATOMIC
MASS
7.5% of the time, Lithium exists as Lithium-6, with 3
protons and 3 neutrons.


The other 92.5% of the time, it exists as Lithium-7,
with 3 protons and 4 neutrons.


1.) Write out the equation scientists use to find its
average Atomic Mass.
                 28Si   = 92.23%, 29Si =
AVERAGE
ATOMIC           4.67%, 30Si = 3.10%
MASS                Avg. Atomic mass of
                   Si = ______________
92.23% of the time, Silicon exists as Silicon-28, with
14 protons and 14 neutrons.
4.67% of the time, Silicon exists as Silicon-29, with
14 protons and 15 neutrons.
The other 3.1% of the time, it exists as Silicon-30,
with 14 protons and 16 neutrons.
2.) Write out the equation scientists use to find its
average Atomic Mass.
              Quick Check
Complete the sentences below.

3.) Atoms always have an equal number of
   ____________ and ____________, each of
   which is equal to the atom’s ____________
   number.
4.) Atoms that have unequal numbers of
   neutrally charged ____________ and
   positively charged protons are called
   ____________.
              Quick Check
Complete the sentences below.

3.) Atoms always have an equal number of
   protons and electrons, each of which is
   equal to the atom’s atomic number.
4.) Atoms that have unequal numbers of
   neutrally charged neutrons and positively
   charged protons are called isotopes.
Electron
Organization




 The electrons in an atom are
 organized in energy levels. The
 levels farther from the nucleus
 contain electrons that have more
 energy than levels closer to the
 nucleus.
Electron
Organization
Electron
Organization
Electron
Organization
Electron
Organization
Electron
Organization
   2 electrons – 1st level
   8 electrons – 2nd level
   8 electrons – 3rd level

   5.) Sulfur has an atomic number
    of 16. How many atoms does it
    have in each level?
   Draw a model to answer.
2 – 1st
 level
8 – 2nd
 level
6 – 3rd
 level
Electron
Organization
   2 electrons – 1st level
   8 electrons – 2nd level
   8 electrons – 3rd level

   6.) Magnesium has an atomic
    number of 12. How many atoms
    does it have in each level?
   Draw a model to answer.
2 – 1st
 level
8 – 2nd
 level
2 – 3rd
 level
Look at the outermost energy
level of each of these atoms.
The electrons in an atom’s
outermost energy level are
called that atom’s valence
electrons.
Complete these sentences:
 7.) Sulfur has _____ valence electrons.

 8.) Magnesium has _____ valence electrons.
Complete these sentences:
 7.) Sulfur has 6 valence electrons.

 8.) Magnesium has 2 valence electrons.

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:9
posted:9/28/2012
language:English
pages:41