Bonding 1 Flashcards by Aisling Price

wcompound

substance made up of 2 or more different elements that are chemically combined eg carbon dioxide, water

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octet rule

when bonding happens, atoms tend to reach an electron agreement with eight electrons in the outermost energy level. this is known as a stable outer octet.

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valency

number of hydrogen atoms or any other monovalent element with which each atom of the element combines ie carbon can bond to 4 hydrogen atoms so its valency is 4

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ionic bond

force of attraction between oppositely charged ions in a compound. they are always formed by the complete transfer of electrons from one atom to another. giving and receiving

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transition metal

a metal that forms at least one ion with a partially filled d sublevel. it loses electrons from the 4s sublevel first

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variable valency

there is a very small energy difference between the 4s and 3d sublevel so there can be movement of electrons between these sublevels which leads to ions with different charges. (ions can have more than one charge.)

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how can you tell the charge on a transition metal?

by looking at its name (metals always form + ions) and the roman numerals give us the charge

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what are the 2 elements not considered transition metals

scandium and zinc

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why is scandium not considered a transition metal?

forms only 1 ion (Sc+3)
0 electrons in the 3d sublevel ie not partially filled
does not form coloured solution

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why is zinc not considered a transition metal.

forms only 1 ion (Zn+2)
10 electrons in the 3d sublevel ie not partially filled
does not form coloured solution

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which comes first when naming a compound

metal then the non metal

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what is the name for a neg ion

anion

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what is the name for a pos ion

cation

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what sign is used to show an ionic bond in a diagram

an arrow

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what must be shown outside of the brackets in an ionic bond diagram

the charge

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what symbols are used to show electrons in ionic bonding diagrams

dots and crosses

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what does a chemical formula tell us

how many atoms of each element there is in a compound

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what charge do ionic compounds have?

neutral ie balanced

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in what circumstances does crossing the charges on an ion not work?

if the numbers in the charges are the same (they cancel)
if the charges have a lowest common multiple ie 4 and 2 becomes 2 and 1

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what are the steps in finding a chemical formula?

what group is each element in
decide what charge each ion has
balance the charges by crossing the numbers

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what is a polyatomic ion?

ions that have more than one atom

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hydroxide

OH-

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nitrate

NO3-

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hydrogencarbonate

HCO3-

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permagonate

MnO4-

carbonate

CO3-2

chromate

CrO4-2

dichromate

Cr2O7-2

sulphate

SO4-2

sulphite

SO3-2

thiosulphate

S203-2

phosphate

PO4-3

ammonium

NH4+

how do you write the chemical formula of a polyatomic ion?

same as normal except for when you have more than one of the polyatomic ion you put brackets around it and then the amount after them

molecule

a group of neutral atoms joined together and does not contain any ions.

how are covalent bonds formed

between 2 non-metals sharing pairs of electrons

why are bonds formed

so that atoms can have a full outer octet meaning it becomes more stable

why are nobel gases never involved in bonding?

they already have a stable outer octet and are highly unlikely to forms bonds with themselves MONOATOMIC!!!!

what energy level do we draw in covalent bonding

only ever the outer energy level

give 3 differences between ionic and covalent bonding

ionic: conducts electricity when molten or in solution high melting and boiling points hard and brittle covalent: does not conduct electricity low melting + boiling points soft

why do ionic substances conduct electricity when molten or in solution

for a substance to conduct electricity charge has to be able to move. when ionic substances are solid the ions are trapped in a 3D crystal lattice and are unable to move when ions become molten or are dispersed in solution, they become free to move and are able to conduct electricity

what are lone pairs

a pair of electrons not involved in bonding

how many of each sigma and pi is there in a single bond

1 sigma

how many of each sigma and pi is there in a double bond

1 sigma 1 pi

how many of each sigma and pi is there in a triple bond

1 sigma 2 pi

what are the 2 types of covalent bond

sigma and pi

sigma bond

formed by the head on overlap of atomic orbitala

pi bonding

formed by the sideways overlap of p,d and f orbitals

what happens when double bonds form?

first a head on overlap of 2 p orbitals (sigma) then a sideways overlap of 2 p orbitals (pi)

give 4 differences between a sigma and a pi bond

sigma: formed first formed by head on overlap of orbitals involves all orbitals more overlap of orbitals(area) pi: formed after a sigma bond formed by the sideways overlap of orbitals does not involve s orbitals less overlap of orbitals

what does VSEPR stand for

valence shell electron pair repulsion

what is always the start of our answer for "explain/account for the shape"

LP/LP > LP/BP >BP/BP <----------------------- repulsion

linear

180 2 bond pairs AB

trigonal planar

120 3 bond pairs AB3

tetrahedral

109.5 4 bond pairs AB4

pyramidal

107 1 lone pair, 3 bond pairs AB3

v-shaped

104.5 2 lone pair 2 bond pairs AB2

what forms an ionic bond

a metal and non metal

why do atoms bond?

so they can get a stable outer octet

when do ionic bonds form

when one atom (the metal) donates an e- and another accepts it

what determines the charge on an ion

the no of e- it has lost or gained

why is the boiling point of ionic compounds so high

an ionic compound contains a cation and an anion which are held together by a strong electrostatic force the ions are arranged in a 3D crystal lattice the unit cell repeating in all directions ie it takes a lot more energy to overcome these bonds

in what way are ionic molecules arranged

the ions are arranged in a 3D crystal lattice the unit cell repeating in all directions for example in NaCl each Na+ ion is surrounded by 6 Cl- ions

where are transition metals found

d block

what are the properties of transition metals

`they form highly coloured solutions frequently used as catalysts

what does inert mean

doesn't form bonds/react

why are lone pairs important

determining the shape of a molecule

what do you need to mention when talking about an atom gaining/loosing e- in an ionic bond?

which sublevel the e- is going to/from

from what sublevel do transition metals loose e- from first?

what charge do ionic compounds have

neutral

what do we say when explaining shape

lp/lp>lp/bp>bp/bp <----------------------- repulsion state how many lp and bp are on the central atom and explain based on repulsion theory