1. Earth Science Chapter 3 Section 2
Combining Matter
Earth Science
Chapter 3
Section 2

2. A substance that is composed of atoms of two or more different elements that are chemically combined
Examples:
Water- two Hydrogen and 1 one Oxygen atoms.
Table Salt- 1 Na (Sodium) and 1 CL (Chlorine) atoms
Compounds have different properties from the atoms that make them
Compounds

3. Chemical Formulas Compounds represented by chemical formulas Examples:
Include the symbol for each element present
Also includes number of each atom in subscript
If there is only one atom, no subscript is present
Examples:
H20= 2 Hydrogen, 1 Oxygen atoms
NaCL= 1 Sodium and 1 Chlorine atoms
Chemical Formulas

4. Elements stabilize when outermost energy levels are full- chemical bonds can achieve this
Force that holds together the elements in a compound
Stability achieved by sharing electrons
Covalent Bonds:
The attraction of two atoms for a shared pair of electrons that hold the atoms together
Covalent Bonds

5. Covalent Bonds

6. Molecule
Composed of two or more atoms held together by a covalent bonds
No electrical charge- protons and electrons match
A compound comprised of molecules is called a molecular compound
Molecules

7. Polar molecules Electrons of water are not shared equally.
Hydrogen electrons spend more time around oxygen
Polar molecules have a slightly positive and slightly negative end.
Polar molecules

8. Ionic Bonds Ionic Bonds
The attractive forces between two ions of opposite charges
One or more electron are removed from an atom and attached to another atom
Results:
The positive ion attracted to the negative ion
Molecules formed by ionic bonds are called ionic compounds
Ionic Bonds

9. Table Salt
Outermost electron from Sodium atom is taken by Chlorine.
Ions Na+ and Cl- are formed.
The charges of the ions of Na+ and Cl- attract each other.
Ionic Bonds

10. Metallic Bonding In metals Electrons are shared by all atoms
Not just adjacent atoms
a group of positive metal ions surrounded by freely moving negative electrons
Allows metals to conduct electricity
Metallic Bonding

11. Metallic Bonding Configuration of metallic bonding
Metals can be deformed
When hammered, atoms are moved aside
Only the shape is changed
Metallic Bonding

12. Chemical Reactions Compounds can break down into simpler substances
The change of one or more substances into other substances
Reactions described in chemical equations
Chemical Reactions

13. Chemical Reactions When a chemical equation is written
There must be the same number of specific atoms on each side of the equation
Same amount of matter before and after the reaction
Called a balanced equation
Chemical Reactions

14. Mixtures and Solutions
Combination of two or more compounds that retain their identities
Example:
Salt and pepper
Nuts and bolts
Heterogeneous mixture
Particles can’t be distinguished from each other and retain their original properties
Examples:
Sugar water
Molten rock
Metal alloys
Homogeneous mixture
Mixtures and Solutions

15. Mixtures and Solutions
Can be solid, liquid or gas
solutions
mixture
Mixtures and Solutions

16. Acids and Bases Acids Bases
Solution containing a substance that produces hydrogen ions (H+)
Loses an electron
Ph value reading below 7
Lower ph, the more acidic
Substance that produces hydroxide ions (OH-) in water
Base can neutralize an acid
Ph value reading above 7
Higher the ph, the more basic
Acids and Bases