Bonding and structure Flashcards

1
Q

what are ions

A

charged particles

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2
Q

what kind of ion do non metals make

A

gain electrons so negative ions

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3
Q

why are ions formed

A

the atom is trying to get a full outer shell of electrons

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4
Q

what is the relation between group number and the ion formed by those atoms

A

all produce ions with the same charge

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5
Q

what is ionic bonding

A

metals react with non metals, metals loses an electron and non metals gain one. This causes atoms to have opposite charges so they are strongly attracted to one another. this holds the ions together in an ionic compound

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6
Q

how do you represent the charge of an ion in a dot and cross diagram

A

e.g 1+ or 3+ in the top corner outside the bracket

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7
Q

ionic compounds have a structure called what

A

giant ionic lattice

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8
Q

pros and cons of dot and cross diagrams

A

good for showing how ionic compounds are formed

dont show structure of compound, relative sizes or how they are arranged

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9
Q

pros and cons of 3d models

A

show relative sizes of ions and the pattern in an ionic crystal.
only let you see outer layer of compound

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10
Q

pros and cons of ball and stick models

A

show regular pattern, show how ions are arranged, suggest crystal extends beyond what is shown, show relative sizes
sometimes ions are not shown to scale and they suggest gaps are between the ions

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11
Q

what is the boiling points like for ionic compounds

A

high

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12
Q

what is the solubility like of ionic compounds

A

most easily dissolve in water

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13
Q

what is the electrical conductivity of ionic compounds like

A

don’t conduct when solid because ions are held in fixed positions

do when melted or dissolved because then ions are free to move

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14
Q

what is covalent bonding

A

a pair of electrons is shared between 2 atoms to get full outer shells.

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15
Q

why are covalent bonds strong

A

positively charges nuclei is attracted to shared electrons by electrostatic forces

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16
Q

what atoms use covalent bonds

A

non metals

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17
Q

pros and cons of displayed formula

A

shows how atoms are connected in large molecules

dont show 3d structure or which atoms the electrons in the covalent bond have some from

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18
Q

what are simple molecules

A

a few atoms joined by covalent bonds.

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19
Q

what is the bonding of hydrogen

A

one shell with one electron in it so a single covalent bond

20
Q

what is the bonding of chlorine

A

two chlorine atoms share one electron

21
Q

what is the bonding in hydrogen chloride

A

2 atoms share one electron. so single covalent bond

22
Q

what is the bonding in methane

A

carbon has 4 outer electrons so it has 4 single covalent bonds with 4 hydrogen atoms

23
Q

what is the bonding in water

A

oxygen has 6 outer electrons so bonds to 2 hydrogen atoms

24
Q

what is the bonding in nitrogen

A

nitrogen has 5 electrons in outer shell so 2 nitrogen atoms share 3 pairs of electrons, making a triple bond

25
Q

what is the electrical conductivity of simple molecules

A

dont conduct. no ions or free electrons

26
Q

what is the melting/ boiling point like of simple molecules

A

low so mostly gasses or liquids at room temperature. because the intermolecular forces are very weak, and these are the ones that have to be overcome to melt or boil.

27
Q

what is a trend in melting and boiling points of simple molecules

A

as they get bigger, intermolecular forces increase so more energy is needed to break them.

28
Q

what is a polymer

A

consist of lots of long molecules made of repeating sections, joined by covalent bonds and formed when lots of small units link together.

29
Q

what is the shortest repeating section of a polymer called

A

repeating unit

30
Q

how do you write down the molecular formula of a polymer

A

write down formula of reaping unit, put in a bracket and write a little n in the bottom corner

31
Q

what are the melting points of polymers like

A

higher than simple covalent structures because the intermolecular forces increase as the molecules get bigger. still weaker than than ionic or covalent bonds

32
Q

what are macromolecules

A

giant covalent structures e.g diamond and graphite. to melt you have to overcome the covalent bonds between the atoms so they have high melting points.

33
Q

what is the structure of diamond and properties

A

each carbon atom have 4 bonds with other carbon atoms, forming a ridged structure. Does not conduct electricity

34
Q

what is the structure and properties of graphite

A

each carbon atom has 3 covalent bonds
arranged in hexagons
no covalent bonds between the layers- held together by week intermolecular forces so free to move over each other
so soft and slippery- ideal lubricating material
high melting point as covalent bonds need a lot of energy to break
each carbon atom has one delocalized electron so conducts electricity

35
Q

what is graphene

A

a sheet of carbon atoms joined together in hexagons. basically a single layer of graphite

36
Q

what are the properties of graphene and what are they used for

A

very strong
very light so added to composite materials to improve strength without adding weight
can conduct electricity so can be used in electronics

37
Q

what are fullerenes

A

hollow molecules of carbon shaped like tubes or balls. usually in hexagons, pentagons and heptagons

38
Q

what are nanotubes

A

fullerenes which are tiny carbon cylinders, good conductors of heat and electricity

39
Q

how are fullerenes used in medicine

A

cage other molecules so can deliver a drug to where its needed in the body in a highly controlled way

40
Q

how are fullerenes used as a catalyst

A

huge surface area to increase ror

41
Q

how are fullerenes used as lubricants

A

coating machine parts reduces friction

42
Q

how are fullerenes used to strengthen materials

A

nanotubes have high tensile strength

43
Q

how does metallic bonding work

A

electrons in outer shell of metal are delocalized. there is a strong force of attraction between negative charge of electrons and positive charge of the ions which holds metal together in a giant structure.

44
Q

why are metals malleable

A

atoms are held together in a regular structure so the atoms form layers that are able to slide over one another

45
Q

why are alloys stronger than metals

A

different elements have different sized atoms so when they are mixed it will distort the layers.

46
Q

what is brass an alloy of

A

copper + zinc