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CHEMISTRY

2. 1. Atoms
Smallest unit
nucleus: center/core is most of the mass of the atom
a. protons: +
b. neutrons: 0
electron cloud: outermost level

3. 1. Atoms
Ion: charged atom due to gaining or losing electrons ( Na vs Na+ )

4. 2. Element
Pure substance that can’t be broken into other types of matter
Each element has its own symbol that uses 1 or 2 letters

5. 3. Compounds
Substance made of two or more elements
Ex: H2O, NaCl

6. 4. Bonds covalent bonds (strong): 2 or more atoms share electrons
ionic bonds (weak) : attractions between +
and – ions by transferring electrons

7. 5. Chemical Reactions (rxn)
EX. NaOH + HCl  NaCl + H2O
reactants: left side
products: right side
Exothermic: release energy like heat, explosion, light etc.
Endothermic: requires energy to occur and takes it from the environment- feel cold

8. 6. Activation Energy energy needed to start a rxn

9. NEED TO MEMORIZE THE FOLLOWING ELEMENTS AND COMPOUNDS FOR YOUR QUIZ AND TEST!
H: hydrogen
O: oxygen
N: nitrogen
C: carbon
Na: sodium
Cl: chlorine
K: potassium
S: sulfur
COMPOUNDS
H2O: water
NaCl: sodium chloride/salt
H2SO4: sulfuric acid
HCl: hydrochloric acid
NaOH: sodium hydroxide
CO2: carbon dioxide
O2: oxygen gas

10. 7. Acid Acid: a solution in which [H+] > [OH-] Acid Properties
tastes sour, highly corrosive, pH < 7

11. 8. Base Base: a solution in which [H+] < [OH-]
Base Properties: tastes bitter, feel slippery, pH >7

12. 9. Neutral
Pure Neutral water has a pH = 7

14. 10. pH Scale
pH: is a scale that measures the relative concentrations of hydrogen (H+) and hydroxide (OH-).
One unit of change in pH = a change in 10x the acidity of basicity

15. 10. pH power of Hydronium
Measures acidity (from 0-14) and how much H+ is present.
The closer to 0, the more H+ ions
0 up to 7 = acid
= neutral
over 7 = base/alkaline
Can use indicators to tell the pH ( phenol red, pH paper, litmus, BTB)