chemistry - unit 5: semester 1

ionic bonding >

a bond formed when one atom gives up one or more electrons to another atom to achieve an octet

ionic bonding is an exchange of _______

electrons

electrons transfer from the _____ electronegative element to the more electronegative element

less

less electronegative = 

metals 

more electronegative =

nonmetal

what is electronegativity?

the ability of an atom to attract electrons to it

what group is the most ionic in nature?

17

why won’t noble gases create ionic bonds? 

they already have 8 valence electrons (octet)

how many valence electron can helium and hydrogen have maximum?

2

electronegativity differences can be used to predict if a bond will be _______, polar covalent or ionic

covalent

less than 0.5 is what kind of bond? 

non-polar covalent 

0.5-2.0 forms what kind of bond?

polar covalent

more than 2.0 forms what kind of bond?

ionic

what do ionic bonding form? 

ionic crystal structures 

describe an ionic crystal structure >

highly organized

what are ionic crystal called?

crystal lattice

lattice energy >

measures bond strength

what are some other names for lattice energy?

salts or formula units

what is lattice energy do? 

it is the energy required to break ionic solid into separate ions 

stability > 

atoms from bonds to reach their lowest potential energy state 

which compound would have the strongest bonding based on lattice energy?

ScN

what else can you use to measure the strength of a bond?

bond length

when melted, molten, or dissolved in water, what can ionic bonds conduct? 

electric current 

why is there an electric current when ionic bonds and water mix?

the orderly arrangement of ions is broken and the ions are free to move around

are ionic bonds soluble?

sometimes

what does soluble mean?

dissolvable in water

what kind of melting and boiling points do ionic compounds have?

high

what are ionic bonds at room temperature?

solid

what is bonding in ionic compounds? 

metals and nonmetals 

are there high electronegativity differences in ionic compounds?

yes

what gets all of the electrons?

the nonmetals (the ones with the negatives in the brackets)

in ionic bonding, the atoms go from being neutral to being…

charged

what does the subscript tell you?

how many atoms there are

DON’T FORGET TO DRAW A 8 DOTS ON THE NEGATIVE BRACKETED ATOM

what does covalent bonding contain?

polar covalent and non-polar covalent

intramolecular forces > 

forces between atoms to form compounds 

covalent bond >

a sharing of electrons between non-metal atoms

when is a covalent bond formed?

when atoms share one or more pairs of electrons

polar covalent >

electrons are not shared equally

non-polar covalent > 

electrons are shared equally 

electronegativity >

the ability of an atom to attract electrons to itself

less than 0.5 >

covalent

0.5-2.0 > 

polar covalent 

more than 2.0 >

ionic

what do covalent bonds break into?

its ions

what are covalent bonds at room temperature? 

liquids, soft solids, or gasses

what are some examples of soft solids?

water, sugar, carbon dioxide, and graphite

what are the melting points and boiling points of covalent compounds?

low

how do covalent compounds conduct electricity? 

poorly in all phases 

can covalent compounds conduct electricity?

yes but very poorly

are covalent compounds soluble in water?

mostly not

what are examples of polar compounds that are soluble? 

ethanol, ammonia 

bond energy > 

the energy required to break a chemical bond 

what does bond energy correspond to?

bond length

what is the relationship of a bond energy? 

inverse 

what does the short bond equal?

higher energy

what is included in the covalent compounds?

diatomic elements

diatomic elements > 

molecules formed of only two atoms of the same element

diatomic elements are all _______

gases 

what do diatomic elements form?

molecules

what are the diatomic molecules?

H(2), N(2), O(2), F(2), Cl(2), Br(2), I(2)

what do diatomic elements form?

non-polar 

diatomic elements are never found in _________ singularly

nature

what are diatomic elements ALWAYS?

non-polar

molecule =

diatomic elements and it forms a bond with itself 

polyatomic ions >

group of covalently bonded non-metal atoms

what characteristics does polyatomic ions?

molecular and ionic

the charge result form and ______ of electrons (-) or a ___________ or electrons (+)

excess, shortage 

description of covalent bonds >

• non-metal

• shared electrons

• low melting and room temperature boiling points

• liquids and gases at room temperature

• relatively soft (organic compounds)

• weak bonds

• does not normally conduct electricity

• insoluble in water

• electron orbitals overlap

what are two exceptions of the octet rule?

hydrogen and helium

bonding electrons >

two electrons holding the element together

lone pairs > 

two electrons connected to only one atom 

if carbon is the compound, where does it go?

in the center

what always connects to the central atom?

terminal atoms 

if the compound does not follow the rules, the least __________ will be in the center

electronegative 

polar >

the covalent bond between atoms has a large/uneven difference in sharing electronegativity

what is created in polar?

dipole

dipole > 

a bond or molecule whose ends have opposite charges 

non-polar > 

if the covalent has little or no electronegativity difference (even sharing) 

what is polar covalent at room temperature?

liquids

what is the melting and boiling points of polar covalent?

lower

is polar covalent soluble in water? 

yes 

what is non-polar covalent at room temperature?

gasses, some liquids and soft liquids

what kind of gas is non-polar covalent?

volatile

volatile gas >

evaporates easily

what is the boiling and melting points of non-polar covalent?

low

what is non-polar covalent in water? 

insoluble 

what are non-polar covalent always?

diatomic molecules

in polar covalent what are the charges?

one end of the molecule is slightly negative and the other is slightly positive

in polar covalent, what is the position of the central atom? 

two different elements surrounding the central atom 

for polar covalent, are there unshared electrons? where are they?

there are unshared electron pairs but only around the center to be considered this

in non-polar, what is the position of the central atom? 

only one type of element surrounds central atom

in non-polar covalent, are there any shared electrons around the center? 

no 

intramolecular forces > 

bonds between atoms of a molecule 

what are the types of intramolecular forces?

ionic, covalent, and metallic

in forming these bonds, atoms will attain what?

noble gas configuration

noble gas configuration > 

full valence shell, a lower energy state and greater stability 

is intramolecular forces stronger than intermolecular forces?

yes

intermolecular forces >

bonds between molecules

what do the intermolecular forces hold together? 

liquids and solids