Chemical Bonding Flashcards
Chemical bond
Formed to decrease potential energy and increase stability, attractive force between atoms/ions, binds together as unit
Covalent bonds
Electrons are shared between atoms in molecules or polyatomic ions
Ionic bonding
Cations and anions are attracted and held together by electrostatic forces
Polar covalent
Unequal electron attraction, partially charged poles, asymmetric electron density
Nonpolar covalent
Equal share of electrons, symmetrical electron density
Which atom will pull electrons more?
The one with higher electronegativity
What is the range of difference in electronegativity for a nonpolar covalent bond?
Less than or equal to 0.4
What is the range of difference in electronegativity for a polar covalent bond?
(0.4,2.1]
What is the range of difference in electronegativity for an ionic bond?
Greater than 2.1
Crystaline solid
3D network of cations and anions with mutual attraction
Lattice energy
Amount of energy given off by forming 1 mole of an ionic crystalline solid, indicates strength of ionic bonds
Formula unit
Chemical formula for ionic compound, ratio of ions in crystalline structure
Properties of ionic compounds
High melting and boiling points, most are solid at room temperature, hard, brittle, rigid, conduct electricity when molten or dissolved but not when solid
Anion
Nonmetallic atoms that gained valence electrons
Cation
Metallic atoms that lost valence electrons
Polyatomic atom
Group of covalently bonded ions with a net charge for the group
Mole
Amount of a substance with 6.022*10^23 particles, molar weight of an element is the atomic mass in grams
Molar mass
Mass of 1 mol of a pure substance, g/mol
amu
Atomic mass unit
STP
Standard temperature and pressure, 0℃, 1 atmosphere
What is the molar volume of gas at STP?
22.4L/mol
Percent composition
Relative amounts of each element in a compound
Empirical formula
Lowest whole number ratio of the atoms of an element in a compound
Microscopic
Atoms
Macroscopic
Moles
How do you get the empirical formula of a compound from its percent composition?
Assume there are 100g of the compound so the percent is the amount of grams, divide the amount of element in grams by the element’s atomic mass to get the amount of moles, divide all molar quantities by the smallest value (repeat or multiply all quantities to get whole numbers or close)
How do you get the chemical formula from the empirical formula and molar mass?
Find the molar mass of the empirical formula, divide the molar mass of the compound by the molar mass of the empirical formula, multiply the empirical formula numbers by N (compound molar mass/empirical formula molar mass)
Isolated atoms
Monatomic, single atoms
Molecule
Smallest electrically neutral unit with properties, nonmetals, compound or just one element
Molecular compounds
Low melt/boil points, usually gas/liquid, 2 or more nonmetals, unit is molecule
Ionic compounds
From joining metallic cations and nonmetallic anions, electrically neutral, usually solid crystals, high melting temperature, unit is formula unit
7 diatomic elements
Hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, iodine (BrINClHOF)
Stock system
Uses roman numerals in parentheses to indicate numerical value (how much positive charge does a transition metal have)
Which transition metals don’t use Roman numerals and what are their charges?
Silver (Ag) = 1+ charge
Cadmium (Cd) = 2+ charge
Zinc (Zn) = 2+ charge
Binary compounds
2 elements, ionic, name is 2 elements then change anion
Molecular compounds
Only nonmetals, smallest is molecules, charges don’t mean anything, name tells number
Number prefixes
1 = mono-
2 = di-
3 = tri-
4 = tetra-
5 = penta-
6 = hexa-
7 = hepta-
8 = octa-
9 = nona-
10 = deca-
Exceptions/changes to prefix usage
Don’t use mono- for the first element if there’s only one of them, avoid double vowels by removing the end vowel of the prefix except with di- and tri-
