1. UNIT 2 – Matter and Atoms

2. What is Chemistry??
Chemistry: the study of non-living matter, and the changes non-living matter undergoes.
Matter: anything that has mass and takes up space.

3. All matter in the world is either a pure subtance or mixture.

4. Pure sub-stance that is made up of only one type of atom
Element -
Pure sub-stance that is made up of only one type of atom
Pure Substance-
Matter that always has exactly the same composition – the properties are fixed
Compound – Substance that is made of more than one type of atom

5. (Pure) Substance- Element – Compound – Matter that always has exactly
the same composition – the
properties are fixed
Element –
A substance that cannot be
broken down into simpler
substances
Compound –
A substance that can
be broken down into
those simpler substances
Properties differ from those
of the substances from
which it is made
(water – H and O)
Contains only one
type of atom
Ex: aluminum, carbon
oxygen, nitrogen,
mercury
Always contains two or more
elements joined in a fixed
proportion (H20)

6. Properties differ from those of the substances from which it is made
So let's think about it...
Water is H O 2
At room temperature...
Hydrogen is a gas
Oxygen is a gas
water is a liquid

7. Mixtures – properties can vary because the composition is NOT fixed
Individual properties: tend to retain some properties of their individual substances (ex: Salsa)
Homogeneous Mixtures – parts are so evenly distributed that it is difficult to distinguish one substance from another. (ex: Kool-Aid)
Heterogeneous Mixtures– parts are noticeably different from one another (ex: sand)

8. Homo - same
Hetero - different

9. Mixtures Continued Solutions
A mixture in which you cannot see the different parts (homogenous)
Has the smallest particles
Do not separate into layers over time
Light passes through them, particles
don’t scatter light (too small)
Cannot be separated by a filter
Example: sugar in hot water;
windshield wiper fluid; Kool-aid

10. Mixtures Continued Colloids “Cloudy” mixture Medium-sized particles
Do not separate into layers
Cannot use a filter to separate the parts
Particles scatter light
Examples: milk, fog, Jello

11. Mixtures Continued Suspensions
A heterogenous mixture-you can see the different parts.
Large particles.
Will separate into layers over time
Can use a filter to separate parts
Particles scatter light
Examples: Muddy water;
Italian salad dressing, salsa.

12. Suspension
Colloid

13. Solution
Contact Lens Cleaner
Colloid
Milk
Suspension

14. Structure of the atom Electron, (-) charge Proton, (+) charge
(smallest part of an element)
Electron, (-) charge -
Proton, (+) charge +
Neutron, (0) charge - - +
These are called subatomic particles… + + -
This is called the Nucleus

15. ELECTRONS NEGATIVE CHARGE (-1) Orbit the nucleus
Light in mass (1/1836 of a proton)

16. PROTONS POSITIVE CHARGE (+1) Found in the nucleus (center) of an atom
Heavy in mass (1 atomic mass unit, 1amu)

17. NEUTRONS NEUTRAL (0) CHARGE Found in the nucleus
Heavy in mass (1 atomic mass unit,1amu)

18. Number ofprotons or electrons. All normal atoms are neutral.
READING ELEMENTS ON THE PERIODIC TABLE
Atomic Number C 6
12.01
Number ofprotons or electrons.
Unique to each element.
All normal atoms are neutral.

19. C 6 12.01 Mass Number (rounded to whole number)
READING ELEMENTS ON THE PERIODIC TABLE C 6
12.01
Mass Number
(rounded to whole number)
Number of Neutrons
Number of Protons

20. The AVERAGE mass number of all the different isotopes of an element.
READING ELEMENTS ON THE PERIODIC TABLE C 6
12.01
Atomic Mass
The AVERAGE mass number of all the different isotopes of an element.

21. Electron Configuration
The arrangement of electrons of an atom.

22. Electrons are arranged in areas that surround the nucleus
Electrons are arranged in areas that surround the nucleus. These areas are called energy levels.

23. The first energy level can hold 2 electrons.
The second energy level can hold 8 electrons.
The third energy level (and all others) can hold 8 electrons.

24. Atoms always fill the energy levels from the inside out.
Once the energy level closest to the nucleus has 2 electrons, the next energy level begins to be filled.

25. Ions Atoms want 2 or 8 electrons in valence shell
Atoms having more or less electrons than they normally do.
Atoms want 2 or 8 electrons in valence shell