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Matter

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					                                                      Matter
•    Anything that has mass and occupies space.
•    Everything is made up of matter.
•    Chemistry is the study of matter and the changes that matter undergoes.

Examples:
•   Milk spoils due to a chemical reaction that converts lactose to lactic acid.
•   Iron rusts due to a chemical reaction with oxygen that forms iron (III) oxide (rust).

States of Matter:
•    Solid: has a fixed volume and fixed shape; solids are held together in a rigid, organized structure; solids are
     incompressible.
•    Liquid: has a fixed volume, but no fixed shape; liquids take on the shape of the portion of the container that they
     occupy; liquids are incompressible.
•    Gas: also known as vapor; has no fixed volume and no fixed shape; gases conform to the volume and shape of their
     entire container; gases are capable of being compressed and expanded.




                                                                                                                    1
                                        Classifying Matter
Matter is either a pure substance or a mixture of pure substances.

1)       Pure substance: matter that has a fixed composition and distinct properties; can be an element or a
         compound.
      a)       Elements are substances that cannot be broken down into simpler substances by chemical methods.
               They are the building blocks for all matter.
            i.     An atom is the smallest piece of an element that can exist and still retain the properties of that
                   element. Composed of subatomic particles (protons, neutrons and electrons).




      b)       Compounds are pure substances that can be broken down into simpler substances by chemical
               means (chemical reaction). They can be broken down into the elements which make they up.
               Compounds are still pure substances as they have a fixed composition.
            i.     Molecular compounds: composed of molecules which are small uncharged units. Molecular
                   compounds are typically composed of nonmetals only. Water (H2O) is a molecular compound.
            ii.    Ionic Compounds: composed of positively and negatively charged particles called ions.
                   Typically formed from metals and nonmetals. Sodium chloride (NaCl) is an ionic compound.
            iii.   Recall that ions are formed when an atom loses or gains an electron and thus does not have
                   equal numbers of positively charged protons and negatively charged electrons. Recall that ions
                   with a negative charge are called anions, and those with a positive charge are called cations.
                                                                                                               2
                          Classifying Matter Continued
2)     Mixture: A mixture is matter that contains two or more substances (either elements and/or
       compounds) mixed together. Mixtures can be homogenous or heterogeneous.
       a)    Homogenous mixtures: Uniform throughout (same phase and composition), and will have
             the same properties throughout.
       b)    Heterogeneous mixtures: Not uniform throughout (may contain different phases), and will
             have varying composition throughout.

Problems:

1)     Matter is either classified as a(n) _____ or a(n) _____.

2)     Classify the following as either a pure substance or a mixture:
       A.     Helium
       B.     Potassium iodide (KI)
       C.     A granola bar

3)   Classify the following a an element, compound, or mixture:
       A.      18 K gold jewelry
       B.      Carbon
       C.      Carbon monoxide (CO)
       D.      1% milk




                                                                                                   3
                                      The Periodic Table
•   Groups: The vertical columns.
•   Periods: The horizontal rows.
•   Symbols: The abbreviation for the full element name; some names are based on Latin names.
•   Atomic Number: Tells the number of protons in the element; it is the fundamental identity of an element.
•   Atomic Weight: The weighted average of all the naturally occurring isotopes of an element.




                                                                                                               4
                           Chemical and Physical Change
Physical Change: does not alter the chemical identity of the substance undergoing the change.

Examples:
•   Shattering a ceramic plate
•   Melting an ice cube
•   Boiling water

Chemical Change: a substance is changed into a different chemical substance (or substances); this occurs through a
    chemical reaction.




Chemical changes are shown through chemical equations.

Examples:
•   Rusting of iron: 4Fe (s) + 3O2 (g)  2Fe2O3 (s)
•   Burning of propane gas: C3H8 (g) + 5O2 (g)  3CO2 (g) + 4H2O (g)



                                                                                                                5
                                        Subatomic Particles



The number of protons is given in the periodic table as the atomic number. This is fundamental to the identity of the
element. If the atomic number of an element is 1, then the element must be hydrogen (H). If the atomic number is 2, then
the element must be helium (He).

Electrons are equal to the number of protons in a neutral atom. Electrons can be gained or lost without changing the
identity of the atom; metals commonly lose electrons to form cations; nonmetals commonly gain electrons to form anions.

The number of neutrons can vary without changing the identity of the atom. Two atoms with the same number of protons
but a different number of neutrons are called isotopes. You can determine the number of neutrons in a particular isotope
from the mass number. The mass number is the sum of the protons and neutrons in an atom. Thus, the number of
neutrons can be found by subtracting the atomic number from the mass number.

Problems:
      1) A neutral atom has an atomic number of 7 and a mass number of 15. How many protons, neutrons and electrons
          does this element have? Write the element symbol to represent this particular isotope.

      1) Write the element symbol to represent a neutral atom of carbon-14.

      1) How many protons, neutrons and electrons are in 40K +



                                                                                                                    6
                               Isotopes and Allotropes

Allotropes: Different chemical forms of the same element in the same state. Not to be confused with
isotopes. Allotropes may appear very different in appearance. See the example below for three allotropic
forms of the element carbon:




    Diamond                                    Graphite                                     Buckyball

Isotopes are atoms of the same element with different numbers of neutrons. They behave the same
chemically and physically, but have different weights. See the example below for three isotopes of the element
hydrogen:




                                                                                                            7
                                        Atomic Structure
•   Electrons are not perfectly free to move about outside of an atoms nucleus. Electrons are restricted to certain
    regions of space within an atom called orbitals. An orbital can only house up to two electrons.
      – Electrons occupy energy levels (1, 2, 3…)
      – Within each energy level there are certain sublevels available (s, p, d and f)
      – Within an s sublevel there is one orbital that may contain up to two electrons max
      – Within a p sublevel there are three orbitals that may contain up to two electrons each (6 electrons max)




•   We show the location of electrons through electron configurations.




                                                                                                                 8
                           Problems: Chapter 1 and 3

1)   Write the electron configuration for oxygen.

2)   What element resides in group 7 and period 2?

3)   What element has the symbol Na?

4)   What is the collective name for the elements in group 8A?

5)   What is the atomic number of carbon?

6)   Write the element symbol to represent carbon-12.

7)    Circle the symbol that represents an isotope of nitrogen-14.
     A.      14C

     B.      15N

     C.      15Ni

     D.      14Ni



8)    Classify the following as a chemical or physical change:
     A.     Water boils
     B.     Sodium metal and chlorine gas form sodium chloride
     C.     Sodium metal is sliced into smaller pieces
     D.     Milk sours

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posted:4/21/2013
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