Conversions/Writing Formulas

Question 1

Law of multiple proportions

Answer 1

-When 2 elements come together to form compound
-Take the first element over second element (however many there are)
-Multiple by 1 element/x then cross multiply
Basically taking the denominator and dividing by numerator
-Get numbers and take biggest over smallest (can have two biggest)
-Need to get ratio so round off

Question 2

Radioactivity equations

Answer 2

Alpha Particle/Alpha Decay = 4/2 He (+2) (make equation balanced)
Beta Decay = An electron (0/-1) e
Positron Emission = (0/+1) e

Question 3

Fission

Answer 3

neutron collides into a heavy nucleus, splits nucleus into 2 similarly sized fragments (getting smaller)

Question 4

Fusion

Answer 4

The combo of 2 or more light nuclei to form a heavier one (getting bigger)

Question 5

Isotopes

Answer 5

Atoms of the same element have same number of protons but different neutrons (same atomic number, different mass number)

Question 6

How to calculate average atomic masses of elements

Answer 6

Take mass and amu (into a decimal)
Multiply those 2 then add it to the other calculation
-ex (.75771)(34.96885 cl) + (.6789)(32.778)

Question 7

Ions

Answer 7

result when electrons are added or removed
cation - positively charges but removed
anion - negatively charged but added

Question 8

Binary Compounds - 2 different element groups

Answer 8

contains only 2 diff element groups (ionic)
Positive+Negative element + ide at the end

EX; KCl - potassium chloride

• ionic you always balance out if your given the name

Question 9

Binary compounds containing variable charged elements

Answer 9

transition metal + non metal
-positive element (Roman numeral) + negative element stem + ide at end

EX;
FeCl2 - (cross over) Iron (II) chloride

Question 10

Binary compounds containing two nonmetals

Answer 10

covalent
-less electronegative + more electronegative element + ide

EX
NO nitrogen monoxide

• you don’t balance

Question 11

Acids derived from binary compounds

Answer 11

hydro + negative element stem + ic acid

EX : HCl - hydrochloric
HBr - Hydrobromic

Question 12

Ternary acid compounds

Answer 12

containing oxyanions negative element stems + ours or ic acid (has hydrogen and oxygen in it and another element)

Ite - ous
ate - ic
EX : H2SO3 = sulfurous acid
HNO2 = Nitrous acid

Question 13

Formula Mass

Answer 13

Just the sum of the grams
NO2 (14.0067)+2(15.9994)=46.0

if it asks for mass in grams of ethanol molecule its same formula

Question 14

Chemical formula - percent composition

Answer 14

(mass of the element/molar mass of the compound) x 100

Question 15

Mass percentages

Answer 15

(# of elements)(molar mass of specific part compound)/(Molar mass of whole compound) x 100

Question 16

empirical formula

Answer 16

1. percent to grams (same number)
2. convert to mols from grams (take given number divided by periodic table number)
3. divide mols by lowest mols

Question 17

combustion

Answer 17

combines with oxygen gas and releases making CO2 and H20

• must write state and balance

Question 18

percent abundance

Answer 18

take the mass that’s the whole set it equal to the other masses
ex : 72.747 = (x * 73.768) (x-1 *(74.738))
-distribute out the x’s and then subtract so you get an x number and other number
-minus and divide and you get a number then minus one for the other number