Download Bohr Diagram - shows all e

Chemical Interactions Review
Notes
Valence electron
1) Electron Movement based on what we did
with Happy Atoms
- Look at oxidation number
- count how many it takes to be a noble gas
- look at group/family number
Ex. Na 11 p+
11 e-
N
a
Nucleus protons &
Neutrons
Bohr Diagram - shows all e-
Lewis Dot Structure - shows on valence e- for
bonding
2) Bonding
Ion - atom or group of atoms with a charge (lose or gain valence e-)
Ionic Bond - attractions between two oppositely charged atoms
(includes metals and nonmetals, polyatomic ions)
Ex. Na+1Cl-1 metal and a
nonmetal
Loses 1egains 1eOverall is neutral (charges
cancel)
Covalent Bond - atoms share electrons (nonmetal and nonmetal);
can be polar (the share unequally) or nonpolar (share electrons
equally)
F2
F
H2O
F
CO2
-
O
H
O
C
O
+
H
+
Chemical Interactions Review Notes
8th Grade Science
1
3) Formulas and Equations
Cr = chemical symbol representing an atom
H2SO4 = chemical formula that tells the part of a substance (subscript numbers tell the # of each atom one is understood)
Chemical equation tells what happens in a reaction
6CO2 + 6H2O → C6H12O6 + 6O2 Coefficient numbers tell how many molecules there are (multiplied)
Reactants
Products
4) Naming - words to symbols
1. Find symbols
2. Find charge (oxidation #) if metal or polyatomic ions are used; nonmetals use prefixes
3. Criss-cross (add subscripts unto charges balance)
Ex. Magnesium+2 Chloride-1 ClMgCl2
Cl-
Calcium+2 nitrate-1
Ca(NO3)2
5) Balancing equations - law of conservation of mass
MgCl2 + 2 NaOH ----> Mg(OH)2 + 2 NaCl Double replacement
Polyatomic
1. Count atoms
2. Find odd numbers or large numbers and fix first (leave oxygens and hydrogens until end)
3. Use coeffcients to indicate additionalmolecules
6) Types of Reactions
Decomposition - break down compound 2 KCl ----> 2 K + Cl2
Synthesis - put atoms or molecules together 2 H2 + O2 --- > 2H2O
Single Replacement - only one atom is replaced Mg + 2 ZnCl ---> MgCl2 + 2 Zn
Double Replacement - swap partners MgCl2 + 2 NaOH ----> Mg(OH)2 + 2 NaCl
Activation energy - gets reaction started
Endothermic - absorbs energy - cool
Exothermic - releases energy - hot
KEY QUESTIONS
- How do you know a chemical reaction occurs?
- What happens between atoms and their electrons during a reaction?
Chemical Interactions Review Notes
8th Grade Science
2
7) Acids/Bases
Acids in water ----> H+
Bases in water ---> OHNeutralization - acid and base (double replacement)
HCl
H+ Cl-
+
NaOH
Na+ OH-
----> H2O +
----> water
NaCl
salt (positive base ion with negative acid ion)
pH - level of acidity based on concentration of H+ ions
0 __________________7________________14
More H+
neutral
Less H+
Less OH
More OH-
Chemical Interactions Review Notes
8th Grade Science
3