Chemical Bonding Flashcards

1
Q

what is an ion

A

a charged atom or group of atoms

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2
Q

what happens when an atoms loses one or more electrons

A

it becomes a positive ion called a cation

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3
Q

why do elements in group 1 form ions with a charge of +1

A

because they lose one electron to have a stable electron arrangement

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4
Q

what happens when an atom gains one or more electrons

A

they become a negative ion called a anion

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5
Q

why does the gain of an electron from an atom always produce a negative ion

A

there are more negative charges than positive so the atom becomes a negative ion

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6
Q

what is an ionic bond

A

the electrostatic force of attraction between the positive and the negative ions as a result of electron transfer

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7
Q

what is an ionic bond formed between

A

a metal and a non-metal

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8
Q

what is the structure of ionic compounds

A

a giant ionic lattice

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9
Q

how are ions held together in ionic compounds such as NaCl

A

the strong electrostatic attractions between the positive and negative ions hold the ions together in sold NaCl

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10
Q

what are the properties of ionic compounds

A

they have high melting/boiling points
conduct electricity when melted or dissolved in water
mostly all ionic compounds are soluble in water
solids at room temperature

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11
Q

why do ionic compounds have high melting/boiling points

A

they have a giant ionic lattice with strong electrostatic forces of attractions between the positive and negative ions. A large amount of energy is needed to break the strong ionic bonds and make the ions mobile

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12
Q

why do ionic compounds only conduct electricity when molten or dissolved in water

A

when they are melted or dissolved in water, the ions can move and carry the charge but when the compounds are solid the ions can’t move and just vibrate around their fixed positions

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13
Q

what is a covalent bond

A

a pair of electrons shared between two atoms

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14
Q

what is a covalent bond formed between

A

two non-metals

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15
Q

what is the structure of covalent compounds

A

a simple molecular strucutre

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16
Q

why do larger molecules have higher boiling points than smaller molecules

A

larger molecules have more intermolecular forces

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17
Q

what are the properties of covalent compounds

A

they have low boiling points
they don’t conduct electricity
often insoluble in water but soluble in organic solvents

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18
Q

why do covalent compounds have low boiling points

A

they have a simple molecular structure. They are made up of small molecules with weak forces between the molecules and little energy is needed to break these weak intermolecular forces

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19
Q

why do covalent compounds not conduct electricity

A

there are no free electrons as the outer electrons are all fixed in covalent bonds

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20
Q

why does the metal calcium form an ionic bond but the non-metal silicon forms covalent bonds

A

a calcium atom can lose two electrons to obtain a stable electron arrangement. Silicon cannot lose four electrons or gain four electrons but has to share four electrons

21
Q

what are allotropes

A

different forms of an element in the same physical state

22
Q

what are the allotropes of carbon

A

diamond, graphite, graphene and fullerene

23
Q

what is the structure of diamond

A

giant covalent lattice with strong covalent bonds between the atoms

24
Q

why does diamond have a high melting point

A

many bonds need to be broken to melt it and this needs a large amount of energy

25
Q

why is diamond a hard substance

A

it has a giant covalent lattice with strong covalent bonds between atoms that extend throughout the lattice

26
Q

why does diamond not conduct electricity

A

there are no free electrons as each carbon atom is covalently bonded to four other carbon atoms

27
Q

what are the uses of diamond

A

jewellery, glass cutters, drill bits

28
Q

what is the structure of graphite

A

giant covalent lattice

29
Q

what are the properties of graphite

A

soft and slippery
conducts electricity
high melting point

30
Q

why is graphite soft and slippery

A

graphite has layers of carbon atoms and there are weak forces between the layers so the layers can slide over each other

31
Q

why does graphite conduct electricity

A

as each carbon atom only forms 3 bonds, each carbon atom has one free electron so graphite has delocalised electrons which move along the layers and carry the charge

32
Q

why does graphite have a high melting point

A

graphite has a giant covalent lattice with strong covalent bonds between the atoms therefore many bonds need to be broken to melt it and this needs a large amount of energy

33
Q

what are the uses of graphite

A

electrodes
in pencils
as a lubricant

34
Q

what is the structure of graphene

A

giant covalent lattice with strong covalent bonds between the atoms

35
Q

what are the properties of graphene

A

high melting points
conducts electricity
thin and light
good electrical conductor

36
Q

why does graphene have a high melting point

A

it has a giant covalent lattice with strong covalent bonds between the atoms and many bonds need to be broken to melt it and this needs a large amount of energy

37
Q

why does graphene conduct electricity

A

as each carbon atom only forms 3 bonds, each carbon atom has one free electron so graphene has delocalised electrons. These delocalised electrons move along the layers and carry the charge

38
Q

what is the strucutre of fullerene

A

molecular structure

39
Q

why does fullerene have a low melting point

A

in fullerene there are weak forces between the molecules. Little energy is needed to break these weak intermolecular forces and melt fullerene so it has a low melting point

40
Q

why doesn’t fullerene conduct electricity

A

fullerene has delocalised electrons so it conducts electricity across the surface of the molecule however, fullerene is a poor conductor as there is no movement of electrons between the molecules

41
Q

what are fullerenes used in

A

aircraft, space and car industires

42
Q

what is graphene used in

A

electronics and composites

43
Q

what type of bond is in metalsd

A

metallic bond

44
Q

what is metallic bonding

A

the electrostatic force of attraction between the positive ions and the delocalised electrons

45
Q

what is the strucutre in metals

A

giant metallic latitce

46
Q

why are metals good conductors of electricity when solid

A

delocalised electrons flow through the metal structure and carry the charge

47
Q

why are metals malleable

A

ina metal the ions are held in a lattice structure with no fixed bonds. Therefore when a metal is bent or hammered the layers of ions slide over each other allowing the metal to change its shape without breaking the structure

48
Q

why do metals have a high melting point

A

they have a giant metallic lattice. there are strong electrostatic forces of attraction between the metal ions and the delocalised electrons and a large amount of energy is needed to break the strong attractive forces.