Exam 2 Flashcards
Many main group metals _____ enough electrons to leave them with the same number of electrons as an atom of the preceding noble gas
lose
Many non metals ____ enough electrons to give them the same number of electrons as an atom of the next noble gas
gain
Ion Charge
Moving from far left to far right in the periodic table
positive charges of cations are equal to the group number
Ion Charge
Moving from the far right to the far left in the periodic table
negative charges of anions are equal to the number of groups moved left from the noble gas, excluding the noble gas
monoatomic ion
ions formed from only one atom
polyatomic ions
electrically charged molecules (a group of bonded atoms with an overall charge)
Oxyanions
polyatomic ions that contain one or more oxygen atoms
Naming Oxyanions Rules
Nonmetal forms two oxyanions
-ate is the suffix used for the ion with the larger number of oxygen atoms
-ite is the suffix used for the ion with the smaller number of oxygen atoms
Naming Oxyanions Rules
When a nonmetal forms more than two oxyanions
prefixes are used in addition to the -ate and -ite
per- (largest number of oxygens)
hypo- (smallest number of oxygens)
Ionic bonds
electrostatic forces of attraction
when electrons are transferred, and ions form
Covalent bond
when electrons are shared and molecules form
Ionic compound
a compound that contains ions and is held together by ionic bonds
metals and nonmetals form
ionic compounds
Properties of ionic compounds
solids with high melting point and boiling points
nonconductive in solid form
conductive in molten form, poor conductor in solid form
dissolve readily in water
The formula of an ionic compound must have
a ratio of ions such that the numbers of positive and negative charges are equal
nonmetal and a nonmetal form a
covalent bond
Molecular (covalent) compounds qualities
gases/liquids at room temp
insoluble in water
poor conductors of electricity
low- boiling
low-melting
a cation is formed when
a neutral atom loses one or more electrons from its valence shell
an anion forms when
a neutral atom gains one or more electrons in its valence shell
Bond length
determined by distance which lowest potential energy is achieved
Potential energy
if atoms continue to approach each other, the positive charges of the nuclei start repelling each other, increasing potential energy
What is needed to break chemical bonds
energy
breaking chemical bonds is considered
endothermic
forming chemical bonds
releases energy
Forming chemical bonds is considered
exothermic
pure covalent bond
when atoms forming a covalent bond are identical, the electrons in the bond are shared equally
when the atoms linked by a covalent bond are different, the bonding electrons are
shared but not equally
shifts electron density towards the atom that is more attractive to electrons
electronegativity
measures the tendency of an atom to attract electrons towards itself
nonpolar versus polar is determined by
electronegativity
the more strongly an atom attracts electrons the larger its
electronegativity
electrons in a polar covalent bond are
shifted toward the more electronegative atom
Trend of electronegativity
increases from left to right across a period and decreases down a group
most electronegative element
fluorine
Electron affinity
a measurable quantity of the energy released or absorbed when an isolated gas-phase atom acquired an electron
How do we measure polarity expected in a bond
the absolute value of the difference in electronegativity of two bonded atoms
nonpolar- small
polar- large
As electronegativity difference increases between two atoms the bond becomes
more ionic
Nomenclature
a collection of rules for naming things
Ionic compound naming rules
- name the cation first, followed by the name of the anion
(monoatomic cation is just given the name of the element) - a monoatomic anion is given the name of the element with its ending replaced by the suffix -ide
- a polyatomic ion is just given the name of the ion
Ionic compounds examples
NaCl- sodium chloride
KBr- potassium bromide
Polyatomic ionic compound examples
KC2H3O2- potassium acetate
NH4Cl- ammonium chloride
Naming Ionic compounds containing a metal with a variable charge
Charge of the metal ion is specified by a Roman numeral in parentheses after the name of the metal
examples
FeCl2- iron(II) chloride
FeCl3- iron(III) chloride
Naming ionic hydrates
- name the anhydrous compound (per usual rules)
- add the word hydrate with a Greek prefix denoting the number of water molecules
examples
CuSO4 5H2O- Copper (II) Sulfate pentahydrate
Hydrate
compound, often ionic, that contains one or more water molecules bound within its crystals
Prefix for 1
mono
Prefix for 2
di
prefix for 3
tri
prefix for 4
tetra
prefix for 5
penta
prefix for 6
hexa
prefix for 7
hepta
prefix for 8
octa
prefix for 9
nona
prefix for 10
deca
Rules for naming Molecular compounds
the name of the more metallic element is named first
the name of the nonmetallic is next with the suffix =ide
the numbers of each element are designated by Greek prefixes
examples
SO2- sulfur dioxide
N2O4- dinitrogen tetroxide
Naming binary acids
- the word hydrogen is changed to the prefix hydro-
- the other metallic element name is modified by adding the suffix- ic
- the word acid is added as a second word
example
HF, hydrogen fluoride- hydrofluoric acid
HCl, hydrogen Chloride- hydrochloric acid