Review for Chem Placement test

alpha radiation

large atoms need to decrease in size

• split into 1 He & another atom

beta radiation

too many neutrons to protons ratio

• a neutron converts itself into a proton and a beta particle

positron radiation

too many protons to neutrons ratio

• proton converts itself into a neutron and a positron particle

electron capture

too many protons

• a proton and a beta particle turn into a neutron

mole number

6.02 × 10²³

molar mass

how much one mole of something weighs in grams (g/mol)

• to find molar mass multiply the number of the atom in the compound by its molar mass for each element and then add them together

percent composition

find molar mass of what you want and divide it by the total molar mass of the compound

empirical formula

the most reduced whole number ratio of atoms in a given sample

• convert grams→ moles then divide by smallest mole value

  • if resulting numbers are not whole numbers multiply by the smallest integer that will give you whole numbers

molecular formula

real formula of a molecule

1. calculate empirical formula mass

2. divide the molecules known true molar mass by the empirical formula mass

3. multiply the subscripts of the empirical formula by the integer found by step 2

molarity =

number of moles of solute over the total volume of the solution (moles/liters)

ionic bond

• metals and nonmetals bond together

• electrons transfer from one atom to another to meet the octet rule

• form ions and the opposite charges form an electrostatic attraction(ionic bond)

electronegativity

atom’s ability to attract a bonding pair of electrons

0-0.4 diff in electronegativity

nonpolar covalent

0.5-1.8 diff in electronegativity

polar covalent

1.9+ diff in electronegativity

ionic

attraction

• polar mols attracted to other polar mols

• nonpolar & polar and nonpolar & nonpolar are not attracted to eachother

where are s p d and f shapes on periodic table

orbital notation

fill in each box per level with one electron then go back & add pairs if possible

Boyle’s Law

P1 x V1 = P2 x V2

kelvins =

C +273

Charles’ Law

V1/T1 = V2/T2

Gay-Lussac’s Law

P1/T1 = P2/T2

Combined Gas Law

(P1 x V1)/T1 = (P2 x V2)/T2

all gas mols have

same kinetic E

lighter gas moles move

faster than heavier ones

@STP

1 mol gas = 22.4L

Ideal Gas Law

PV=nRT

R=

0.0821

temp

av kinetic E of its vibrating molecules

• 1 atom → no temp

heat

the sum of all the kinetic E of all of the vibrating molecules

• everything has heat

specific heat capacity =

q /(mass x change in temp)

q is

joules (energy)

q=

m x change in temp x Cp

Cp is

specific heat capacity

cal

Cp for 1 g water

Cal

food calorie

1 Cal =

1 kcal

1 kcal =

1000 cal

cal =

m x change in temp of H₂O

endothermic

break bonds (reactants)

exothermic

make bonds (products)

to find out if reaction is endo or exo thermic

see if the E needed to break the bonds is more or less than the E needed to make the new bonds

to name bases

name of first element + hydroxide

• ie NaOH → sodium Hydroxide

naming acids

1. if H+ not bonded to a polyatomic ion only a singular anion → Hydro__anion__ic acid

2. If H+ is bonded to a polyatomic ion ending in ate → __root word_ic acid

3. If H+ is bonded to a polyatomic ion ending in ite → _root_ous acid

Le Chatleier’s Principle

for equilibrium reactions

reactions want to resist change

1. add/remove chemicals will cause the equilibrium to shift

2. temp up cold side favored, temp down hot side favored

3. pressure(gases)

   1. P up side w/ fewer gas molecules favored

   2. P down side w/ more gas molecules favored

equilibrium reactions

the rate of the forward reaction is equal to the rate of the reverse reaction

pH/pOH equations

1. pH + pOH = 14

2. pH = -log[H+]

3. pOH=-log[OH-]

4. 10^-pH=[H+]

5. 10^-pOH=[OH-]