covalent bonding

what are the exceptions to the octet rule?

1) hydrogen only has 2 atoms 2) beryllium has a max of 4 valence electrons 3) boron compounds are stable with only 6 valence electrons

what is electron affinity?

ability of an atom to attract and hold additional charges

atoms actually move back and forth but maintain an ____ _____ _____

average distance apart

uneven sharing results when there is a great difference in ____________

electronegativity

to predict if a molecule will be polar or nonpolar, study the _____________ __________

electronegativity values

covalent bonds form because _______________________

electrons of one atom are attracted to the positive nucleus of another atom

the more electrons, the more likely _____

electrons will pile up on one side and cause a temporary positive end and temporary negative end on a bond

if 2 atoms begin to move apart, attractive forces between the _____ of one atom and the ______ of the other atom pull them back together

electrons; nucleus

any time a chemical bond forms, _____ is released

energy

what is an exothermic reaction?

energy is released as atoms move from a high energy state to a low energy state when covalent bonds form

nonmetals seek to _____ electrons to make them stable

gain

if a bond has few electrons, it's likely to be a ______

gas

all nonmetals have _____ electronegativity and ______ electron affinity

high

mono

1

what are the guidelines for covalent bonding of unlike atoms?

1) add up valence electrons of each atom 2) divide the total number of electrons by 2 to get total number of electron pairs available 3) element with lowest electronegativity is the central atom 4) hydrogen is always a terminal atom - it can only connect to one other atom because it can only form one bond 5) place one pair of electrons (represented by a dash) between each pair of bonded atoms 6) subtract number of pairs used from number of pairs available 7) place lone pairs around each terminal atom to satisfy octet rule 8) convert one or more terminal atom lone pairs into double or triple bonds - only for CNOPS

what are some intermolecular attraction characteristics?

1) attractions between molecules 2) weaker than ionic or covalent bonds 3) determines if a molecular compound is a solid, liquid, or gas 4) best indicator of strength of intermolecular forces: boiling point

what are characteristics of multiple bonds?

1) commonly formed by carbon, nitrogen, oxygen, phosphorus, sulfur 2) stronger than single bonds 3) increase the electron density between to nuclei. as the electron density increases, the repulsion between the two nuclei decreases. also as the electron density increases, the attraction each nucleus has for the additional bonding electron pairs increases. both of these effects draw the nuclei closer together, shortening the bond length

what are characteristics of ionic bonds?

1) electrons are transferred between atoms having large differences in electronegativity 2) contain a metal and nonmetal 3) strong electrostatic attractions between positive and negative ions 4) formulas given in simplest ratio of elements 5) crystalline structures that are solid at room temperature 6) form crystal lattice 7) high melting/boiling point 8) good conductors of electricity when melted or dissolved

what are the steps in naming molecular compounds?

1) list 1st name of element in compound. if more than one atom is present, include a prefix to indicate that number of atoms 2) list 2nd name of element in compound. always include a prefix indicating number of atoms of 2nd element and use "ide" suffix

what are the three types of intermolecular forces?

1) london forces 2) dipole dipole 3) hydrogen bonding

what are some properties of molecular compounds?

1) low melting and boiling points 2) poor electrolytes - does not conduct electricity well

what are some characteristics of covalent bonds?

1) share electrons between atoms having small differences in electronegativity 2) 2 nonmetals 3) formulas that are given in the true ratio of atoms 4) exist in any state of matter at room temperature 5) low melting/boiling points 6) nonconductors of electricity

what are some characteristics of dipole dipole intermolecular forces?

1) strong intermolecular force 2) forms between polar molecules 3) caused when the positive end of one molecule is attracted to the negative end of adjacent molecules 4) similar to electrostatic forces between ions, but much weaker

what are some characteristics of hydrogen bonding?

1) strongest type of intermolecular force 2) lone pair of electrons has a strong negative charge; the positive end of one polar molecule is attracted to a lone pair of electrons from another molecule 3) usually occurs when H is covalently bonded to F, Cl, N, or O

what are some characteristics of london forces?

1) weakest intermolecular force 2) forms between nonpolar molecules 3) caused by motion of electrons 4) electrons of one atom attracted to positive nucleus of adjacent atoms 5) the more atoms present, the greater the attraction

how many valence electrons do metals have?

1-3

deca

10

v shape, bent, or angular

104.5 degrees

trigonal pyramidal

107 degrees

tetrahedral

109.5 degrees

trigonal planar

120 degrees

linear

180 degrees

di

2

what is covalent bonding an analogy of?

2 equally strong people playing tug-of-war - neither can pull the rope harder than the other one

a covalent compound is a bond between _____ ____________

2 nonmetals

tri

3

tetra

4

penta

5

how many valence electrons do nonmetals have?

5-7

hexa

6

hepta

7

octa

8

nona

9

what are the 7 diatomic molecules?

H2, N2, O2, F2, Cl2, B2, I2

what does a polar covalent bond result in?

a dipole

what does a covalent bond form?

a molecule

what is a dipole?

a molecule with oppositely-charged ends; oxygen pulls the negative pair of electrons closer to it; pulls electrons slightly away from hydrogen atom so molecule has a negative end and a positive end

what is a molecule?

a neutral group of atoms that are held together by covalent bonds

a dash between 2 elements that are covalently bonded and written in lewis dot notation represents

a single covalent bond

inter means

between

_______ a bond requires energy

breaking

what are intramolecular forces of attraction?

chemical bonds which are the attractive forces between atoms with a compound

what is the valence shell electron pair repulsion theory?

electron pairs repel one another so molecules adjust their shapes so that electron pairs are as far apart as possible

___________ values are used to predict the type of bond that will form between the atoms of 2 elements

electronegativity

if electronegativity difference is greater than or equal to 2.0

ionic bond

if the central atom is from PERIODS 3-7, what happens?

it can accommodate more than 4 electron pairs, due to the presence of d orbitals

all diatomic molecules have a _________ shape

linear

if a bond has an average amount of electrons, it's likely a ________

liquid

what state are most molecular compounds at room temperature?

liquids or gases

large atoms have more energy levels of electrons, so there are _____ bond lengths, therefore _____ energy is required to separate atoms

longer; less

covalent compounds are also called ______ compounds

molecular

a double or triple bond requires _____ energy to break than a single bond

more

the higher the boiling point, the _______ _________ the particles are attracted to each other

more strongly

if 2 electrons are shared equally, a _________ is formed

nonpolar covalent bond

if electronegativity difference is less than 0.4

nonpolar covalent bond

a single bond represents _____ pair of electrons shared

one (2 electrons)

in a covalent bond, shared electrons fill the _____ orbitals of both atoms, making them both stable

outer

if electronegativity difference is from 0.5 to 1.9

polar covalent bond

when one atom has a stronger attraction for a pair of electrons than another, a _________ is formed

polar covalent bond

if 2 atoms move too close, the 2 _______ __________ repel each other, and the atoms move apart

positive nuclei

if 2 atoms of the same nonmetal element react with each other, electrons will be _________ _________ between them; neither atom has a greater attraction for the shared electrons

shared equally

when bond lengths are ______, atoms are very close, and ____ energy is required to separate them

short; more

if a bond has a lot of electrons, it's likely a ______

solid

when unlike atoms share electrons, one atom may have a _________ ___________ for the shared pair of electrons

stronger attraction

what is electronegativity?

tendency of an atom to attract a shared pair of electrons

what is bond length?

the average distance (space) between two nuclei that are bonded together

what is bond dissociation energy?

the energy required to break a bond between two covalently bonded atoms

what are intermolecular forces of attraction?

those occurring between molecules and are responsible for properties such as boiling point, freezing point, and physical state

a triple bond represents ______ pairs of electrons shared

three (6 electrons)

a double bond represents _____ pairs of electrons shared

two (4 electrons)

only ________ are involved in bonding

valence electrons

intra means

within