1. Matter and Atomic Structure Section 3.2- How Atoms Combine
Chapter 3
Matter and Atomic Structure
Section 3.2- How Atoms Combine

2. Vocabulary
Compound
Substance composed of atoms of two or more different elements that are chemically combined.
Exp. Water molecule (hydrogen & oxygen)
Exp. Table salt
(chlorine – poisonous & sodium –toxic)

3. Vocabulary Chemical bond
Force that hold the atoms of elements together in a compound.

4. COMPOUNDS
Most compounds on earth are held together by 2 types of bonds:
Covalent bonds
Ionic bonds

5. Vocabulary Covalent bond
Two atoms combine with each other by sharing electrons.
C=caring=sharing
Exp. Water molecule
2 Hydrogen share
Electrons with 1 oxygen

6. Vocabulary
Ion
An atom that gains or loses and electron is a charge particle.
Ionic bond
The attractive force between to ions of opposite charge.
Example Table salt (NaCl)
One of the most common compounds on Earth magnesium oxide (MgO).
Compounds formed by ionic bonding are known as ionic compound.

7. Covalent bond vs. Ionic bond

8. Ions Atoms gain/loose electron from their outermost energy levels.
Anion-When an atom gains an e-, it becomes more negative.
Cation-When an atom looses an e-, it becomes less negative and more positive.

9. Vocabulary Chemical Reaction
Change of one or more substances into other substances.

10. Chemical Reaction
Example- Formation of water H2O

11. Chemical Reaction
Example- Formation of Rust
Fe2O3

12. Chemical Reaction Example- Photosynthesis
Light energy + carbon dioxide + water = glucose + oxygen Q + 6CO2 + 6H2O = C6H12O6 + 6O2

13. Mixture
A mixture is a combination of two or more components that retain their identity.
Homogeneous mixture
Components are NOT recognized easily
(homo=same)
Ex. Coffee
Heterogeneous mixture
Components are recognized easily
(hetero=different)
Ex. Soil

14. Solutions A homogeneous mixture is called a solution.
Solid solution-Metal alloys:
Bronze; mixture of Copper (Cu) and Tin (Sn) atoms,
Brass; mixture of Copper (Cu) and Zinc (Zn)
Liquid solution:
Magma – molten rock/lava
Gaseous solution:
Atmosphere/Air

15. Vocabulary Acid Substance that produces (H+) hydrogen ions in water.
Most common in our environment -carbonic acid
Responsible for the dissolution of limestone; forming caves.

16. Vocabulary Base Substance that produces (OH+) hydroxide ions in water.
A base can neutralize an acid.