Relationship between chemical bond → compound → formula
chemical bond = the force that holds atoms together
compound = one or more chemically bonded elements
formula = indicates the elements in compounds and helps us identify them with names
Empirical vs. molecular formula
Empirical = indicates the relative # of atoms in a compound (found by dividing by the LCF)
molecular = indicates the actual # of atoms in a compound
Ionic compounds involve a ___ of electrons and form between a ___ and a ___
- Transfer of electrons
- A metal (+ cation) and a nonmetal (- anion)
- Formula unit: the smallest collection of ions that are electrically neutral
Covalent compounds involve ___ of electrons and form between a ___ and a ___
Sharing of electrons
- A nonmetal and other nonmetal
- Formula unit: covalently bonded atoms that make up a molecule
Type I ion (which metals)
A metal that only forms 1 type of ion
- metals in 1A - 2A, Ag, Au, Zn, Ga, Al
How do you name a type I ionic compound
Name of cation + base name of anion - ide
How do you name a type II ionic compound
Name of cation (charge of cation in roman numerals) + base name of anion - ide
How do you name a covalent compound
(prefix) + first element, (prefix) + second element
- first element: element with the smallest group number (most left) and/or the greatest row number (most down)
- prefix: indicates the number of atoms of that element
What are the 10 common prefixes for covalent compounds
mono = 1 di = 2 tri = 3 tetra = 4 penta = 5 hexa = 6 hepta = 7 octa = 8. nona = 9 deca = 10
Steps for writing an ionic formula when given the name of a compound (vice versa)
1) determine the metal's charge based on it's group #
2) determine the nonmetal used based on it's base name and it's charge based on the nearest noble gas config.
3) determine how many metal ions are needed to balance (cancel out) the charge on the anion
4) express as the smallest whole number ratio you can (empirical)
How do you name a polyatomic ionic compound
Name of metal + name of polyatomic ion using the common ion table
Formula mass and molar mass of a compound
Formula mass: (# of atoms of 1st element x its molar mass) + (# of atoms of 2nd element x its molar mass)
molar mass: numerically equal to a formula's formula mass in grams (g)
Steps and formula for determining how many molecules are in (x)g of a compound
Given g · (1 mol of compound ÷ its formula mass (g)) · (6.022x1023 ÷ 1 mol) = molecules in compound
1) determine the compound's formula mass (if not given)
2) convert grams → moles → molecules
Steps for determining empirical formula of a compound if given a % composition
1) Assume 100g sample and convert % of each element into decimal of g
2) Convert g of each element into moles using its formula mass
3) Divide mole amount of other elements by element with the smallest # of moles (1:1, 1:2, etc.)
4) Write as the smallest whole number ratio you can
- If dividing results in a non whole number, convert decimal amount into a fraction and multiply entire ratio by denominator
Steps for determining molecular formula of a compound if given an empirical formula and molecular mass
1) find empirical formula if not given
2) find empirical mass by multiplying each elements molar mass by it's subscript in the empirical formula
3) determine how many times the empirical mass would have to be multiplied/divided to obtain the given molecular mass
4) multiply the formula's subscripts by that number to obtain molecular formula
Steps for determining a % composition of a compound if given a formula
1) determine formula mass of the compound
2) for each element, divide (number of atoms of that element · it's molar mass) by the compounds formula mass [(# of atoms of element · element's molar mass) ÷ formula mass]
3) convert that number to a decimal (move 2 decimal places)
4) check to make sure the % of each element adds up to 100%
Type II ion (which metals)
A metal that forms multiple types of ions
- all other transition metals