chemical bonding Flashcards

1
Q

where are noble gases in the periodic table?

A

group 0

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2
Q

how reactive are noble gases?

A

unreactive and stable

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3
Q

why are noble gases stable?

A

valence electron shells are fully-filled with electrons and exist as monoatomic elements

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4
Q

how can atoms achieve a stable noble gas electronic configuration?

A

losing electrons, gaining electrons, sharing electrons

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5
Q

what is an ion?

A

a charged particle formed when an atom loses or gains electrons

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6
Q

what type of ions do metals form?

A

cations (positive ions)

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7
Q

what type of ions do non-metals form?

A

anions (negative ions)

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8
Q

what is a giant ionic crystal lattice?

A

many ionic bonds between the oppositely-charged ions

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9
Q

what features does a giant ionic crystal lattice have?

A

ions held togfether by strong ionic bonds + packed in a regular pattern

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10
Q

what is a strong ionic bond?

A

strong electrostatic forces of attraction between oppositely charged ions

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11
Q

why do ionic compounds have high mp/bp?

A

ions in ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions which requires a large amount of energy

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12
Q

why are ionic compounds usually soluble in water?

A

water molecules can separate the positive ions from the negative ions which causes the ionic compound to dissolve in water

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13
Q

why are ionic compounds usually insoluble in organic solvents?

A

the ions remain in a giant lattice structure in organic solvents

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14
Q

why are ionic compounds usually conduct electricity in molten state or when dissolved in water?

A

in the molten/aqueous state, ions can move freely and can behave as mobile charged carriers to conduct electricity

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15
Q

why are ionic compounds do not conduct electricity in solid state?

A

in the solid state, ions are held in fixed positions in the giant lattice structure and are not free to move

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16
Q

when is a covalent bond formed?

A

when two atoms share valence electrons

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17
Q

what kind of elements can form covalent bond?

A

non-metals of the same elements and atoms of different elements

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18
Q

what is the relationship between bonds and the pair of electrons shared?

A

x pair = x bond

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19
Q

how do most covalent substances exist?

A

simple discrete molecules have simple molecular substances

20
Q

why do covalent molecules with simple molecular structure have low mps/bp?

A

discrete molecules/covalent bonds held by weak intermolecular forces of attraction between the molecules which require little energy to overcome

21
Q

why are covalent molecules with simple molecular structures usually soluble in water?

A

water molecules cannot separate the structure of simple molecular substances

22
Q

what are covalent molecules with simple molecular structures soluble in?

A

soluble in organic solvent?

23
Q

why do covalent molecules with simple molecular structure not conduct electricity in any states?

A

simple molecular substances are neutral discrete molecules and thus do not have any mobile ions or delocalised electrons to acts a mobile charged carriers to conduct electricity

24
Q

what is an allotrope?

A

different forms of the same element

25
Q

how are carbon atoms arranged in a diamond?

A

each carbon atoms forms strong covalent bonds with 4 other carbon atoms tetrahedral arrangement

26
Q

what type of structures do graphite, diamond and silicon dioxide have in common?

A

giant molecular structure

27
Q

why does diamond/silicon dioxide have a high melting and billing point?

A

it has a giant molecular structure with each carbon atom covalently bonded to 4 other carbon atoms in a tetrahedral arrangement, a lot of heat energy s required to overcome the strong covalent bonds between the atoms

28
Q

why cant diamond/silicon dioxide conduct electricity?

A

all valence electrons are used in covalent bonding with the other atoms and thus there are no delocalised electrons to act as the mobile charge carriers

29
Q

why are diamond/silicon dioxide unable to dissolve in water and organic solvents?

A

water or organic solvents are not able to overcome the strong covalent bonds present in the giant molecular structure

30
Q

why is diamond hard?

A

diamond has a giant molecular structure where each carbon atoms form strong covalent bonds with 4 carbon atoms in a tetrahedral arrangement in an extensive network give rise to a rigid and hard structure

31
Q

what can a diamond be used for?

A

tips of cutting tools and polishing hard surfaces because of its high melting point and hardness

32
Q

what is graphite?

A

an allotrope of carbon

33
Q

what kind of structure does graphite have?

A

giant molecular layered structure with each layer having 1 carbon atom forms strong covalent bonds with 3 other carbon atoms forming hexagonal rings of six carbons atoms that join together to form flat layers,

34
Q

what holds together the layers of carbon in graphite?

A

weak intermolecular forces of attraction/Van der Waal’s forces of attraction

35
Q

why does graphite have high mp/bp?

A

graphite has a giant molecular structure where 1 carbon atom is covalently bonded to 3 other carbon atoms in a hexagonal arrangement which requires a lot of heat energy to overcome the strong covalent bonds between the carbon atoms as well as the intermolecular forces of attraction between the layers of carbon atoms

36
Q

why is graphite a good conductor of electricity?

A

in graphite, each carbon atom uses 3 out of 4 of its valence electrons to form strong covalent bonds with 3 other carbon atoms, leaving 1 delocalised valence electrons not used to form a covalent bonds which can act as mobile charge carriers to conduct electricity along the layers of carbon atoms

37
Q

why is graphite insoluble in water and organic solvents?

A

water or organic solvents are not able to overcome the strong covalent bonds present in the giant molecular structure of graphite

38
Q

why is graphite soft and slippery?

A

graphite has a giant molecular structure with strong covalent bonds present in the giant molecular structure of graphite and weak intermolecular forces between the layers,hence the layers are able to slide across each other easily

39
Q

what are applications of graphite?

A

dry lubricant, brushes for electric motor s as it is a good conductor of electricity, made into pencil lead as it is soft and can rub off easily and stick to paper r

40
Q

what is the structure of silicon dioxide?

A

each silicon atom forms covalent bonds to 4 oxygen atoms while each oxygen atoms forms covalent bonds to 2 silicon atoms

41
Q

what is a lattice structure of metal?

A

a regular lattice of positive ions surrounded by a ‘sea of delocalised electrons’

42
Q

what is a metallic bond?

A

the electrostatic forces of attraction between positive metal ions and the ‘sea of delocalised electrons’

43
Q

why do metals have high mp/bps?

A

a lot of heat energy is required to overcome the strong electrostatic forces of attraction between the metal ions and other ‘sea of delocalised electrons’

44
Q

why can metals conduct electricity?

A

the presence of ‘sea of delocalised electrons’ within the metal lattice which acts as the mobile charge carrier and when electricity passes through it, the ‘sea of delocalised electrons’ move from the negative terminal to the positive terminal

45
Q

why are metals are malleable and ductile?

A

the valence electrons are free to move and do not belong to any particular metal atom, when a force is applied to the metal, layers of closely packed metallic cations can slide over one another without breaking the metallic bonds