C2.2 Flashcards

1
Q

periods

A

horizontal rows

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2
Q

groups

A

vertical columns

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3
Q

who created the periodic table?

A

Mendeleev

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4
Q

ions

A

charged particles that have either lost or gained electrons

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5
Q

ionic bonding

A

metal + non-metal

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6
Q

covalent bonding

A

non-metal + non-metal

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7
Q

describe covalent bonding

A

-when non metal atoms react, they need to gain electrons to fill their outer shell
-they can only do this if they share their electrons

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8
Q

what are strong covalent bonds a result of?

A

electrostatic attraction between positive nuclei of the atoms and the pairs of negative electrons that are shared between them

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9
Q

properties of simple covalent bonds

A

-2 or more non metals
-mostly gases
-low melting and boiling points
-don’t conduct electricity
-low density

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10
Q

why do covalent molecules have a low density?

A

molecules are not closely packed together

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11
Q

why do covalent molecules have low melting and boiling points?

A

strong covalent bonds are not what is broken apart it is the weak intermolecular forces between the bonds that is broken

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12
Q

why do covalent molecules have a low conductivity?

A

there must be free moving charged particles to conduct electricity and covalent molecule have no free moving ions

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13
Q

metal properties

A

-malleable
-shiny
-sonorous
-conducts electricity and heat
-solid at room temperature
-ductile
-high density

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14
Q

non-metal properties

A

-not shiny
-brittle
-doesn’t conduct electricity or heat
-variety of states at room temperature
-low density

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15
Q

differences between the old and new periodic table

A

-fewer elements
-no atomic numbers
-gaps

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16
Q

describe ionic bonding

A

during a chemical reaction between a metal and a non-metal, the reacting atoms either lose or gain electrons to achieve a full outer shell

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17
Q

metal ions

A

lose electrons and form cations

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18
Q

non-metal ions

A

gain electrons and form anions

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19
Q

structure of ionic compounds

A

-oppositely charged ions are arranged in a regular way to form a giant ionic lattice

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20
Q

what do giant ionic lattices result in?

A

the formation of crystals

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21
Q

what is the overall net charge of an ionic compound?

A

it has no overall net charge

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22
Q

properties of ionic compounds

A

-high melting and boiling points
-conducts electricity when molten or in a solution
-crystalline and brittle
-soluble in water

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23
Q

why do ionic compounds have high melting and boiling points?

A

the strong ionic bonds must be broken which requires a lot of energy

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24
Q

why do ionic compounds only conduct electricity when molten?

A

in a solid the ions aren’t free to move, in a solution they are free to move and you need freely moving particles to hold a charge

25
Q

why are ionic compounds crystalline and brittle?

A

when you put pressure on the compound, ions who have the same charge come next t each other and repel, causing it to shatter

26
Q

why are ionic compounds soluble in water?

A

chloride ions are attracted to the hydrogen ions, the sodium ions are attracted to the oxygen ions and the compounds are separated by the water molecules because of the oppositely charged attraction

27
Q

malleable

A

capable of being hammered or pressed into shape without breaking or snapping

28
Q

ductile

A

capable of being drawn into thin wires without breaking

29
Q

metallic bonds

A

metal + metal

30
Q

describe metallic bonds

A

strong electrostatic attraction between delocalised electrons and positive metal ions

31
Q

what are the properties of metallic bonds?

A

-high melting and boiling points
-good conductors
-flexible

32
Q

why do metallic bonds have high melting and boiling points?

A

they have very strong metallic bonds which require a lot of energy to break

33
Q

why are metallic bonds good conductors?

A

delocalised electrons are free to move and carry a charge

34
Q

why are metal bonds flexible?

A

the layers can slide over each other which is why they are malleable and ductile

35
Q

alloy

A

mixture of two or more metals

36
Q

allotropes

A

different forms of the same element that have different properties because their atoms are arranged differently

37
Q

properties of giant covalent structures

A

-very high melting and boiling points
-crystalline appearance
-hard
-generally don’t conduct electricity
-insoluble in water

38
Q

why do covalent structures have high melting and boiling points?

A

consists of very strong bonds which require a lot of energy to break

39
Q

why do covalent structures have a crystalline appearance?

A

ordered in a giant lattice structure

40
Q

why are covalent structures hard?

A

made of rigid covalent bonds

41
Q

why do covalent structures generally not conduct electricity?

A

every carbon atom is bonded to other carbon atoms so there are no delocalised electrons left over

42
Q

comparing metals with alloys

A

metal: has regular layers which means they can slide over each other when stretched or bent
alloys: don’t have regular layers as the different type of metal distorts the layers which makes it harder for layers to slide over each other

43
Q

what are giant covalent structures?

A

consists of millions of non-metal atoms joined by covalent bonds and arranged in a repeating regular pattern

44
Q

what are the different abilities of carbon?

A

-forms four chemical bonds to other atoms
-bond itself forming long straight, branched and even ring carbon chains
-form single, double or even triple bonds

45
Q

describe the structure of graphite

A

-made from repeating hexagons that form layers or sheets
-this leaves each carbon with a ‘spare’ electron that isn’t used in bonding, these spare electrons are free to move between the layers
-this means carbon is bonded to three other carbon atoms

46
Q

what is an example of a giant covalent structure?

A

silicone dioxide

47
Q

what are fullerenes used for?

A

lubricants

48
Q

polymers

A

very long covalent molecules

49
Q

LDPE

A

low density polyethene e.g. plastic bags

50
Q

HDPE

A

high density polyethene e.g. hard hat

51
Q

increasing the chain length of polymers

A

-long polymer chains have stronger intermolecular forces than shorter ones
-by making the chains of polymers longer, a stronger and less flexible material is produced with a higher melting point

52
Q

modifying polymers using cross linking

A

-addition of cross links between polymers makes the material tougher, less flexible and increases melting point
-crosslinks are chemical bonds that links polymer chains together

53
Q

thermosoftening polymer

A

gets softer when heated

54
Q

thermosetting polymer

A

gets harder when heated

55
Q

limitations to the particle model

A

-scale of nucleus to the electrons is wrong in most models
-models show bonds as physical structures
-most models do not give an accurate idea of the 3D shape of a molecule
-bond lengths are not in proportion to the size of the atom

56
Q

what are synthetic polymers commonly called?

A

plastic

57
Q

what is an example of a naturally occurring polymer?

A

silk

58
Q

how do polymers form?

A

when lots of small covalent molecules called monomers join together