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schewl >_< > science c3 > Flashcards

science c3 Flashcards

1
Q

How are covalent bonds formed?

A

by atoms sharing electrons.

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2
Q

Which type of atoms form covalent bonds between them?

A

non-metals

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3
Q

Describe the structure and bonding of a giant covalent substance(billions of A, bonded, strong, bonds)

A

billions of atoms bonded together by strong covalent bonds.

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4
Q

Describe the structure and bonding of small molecules(numbers,group,molecules, S covalent,atoms,intermolecular,between M)

A

small numbers of atoms group together into molecules with strong covalent bonds between the atoms and weak intermolecular forces between the molecules

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5
Q

Describe the structure and bonding of polymers.

(many identical M, covalent B, L chain, weak, forces, chains)

A

many identical molecules joined together by
strong covalent bonds in a long chain, with weak intermolecular forces between the chains

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6
Q

Why do giant covalent substances have high melting points?

(L of energy, C bonds, atoms)

A

it takes a lot of energy to break the strong covalent bonds between the atoms

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7
Q

Why do small molecules have low melting points?

(break, I forces

A

only a small amount of energy is needed to break the weak intermolecular forces

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8
Q

Why do large molecules have higher melting and boiling points than small molecules?

A

the intermolecular forces are stronger in large molecules

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9
Q

Why do most covalent substances not conduct electricity?

(not, delocalised E, or I)

A

do not have delocalised electrons or ions

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10
Q

Describe the structure and bonding in graphite.

  • ( each C A,bonded, T others, H rings, layers)
  • (delocalised E, and, W forces, layers)
A
  • each carbon atom is bonded to three others in hexagonal rings arranged in layers
  • it has delocalised electrons and weak forces between the layers
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11
Q

Why can graphite conduct electricity?

(D electrons, move, graphite)

A

the delocalised electrons can move through the graphite

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12
Q

Explain why graphite is soft.

(layers,N bonded,slide)

A

layers are not bonded so can slide over each other

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13
Q

What is graphene?

A

one layer of graphite

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14
Q

Give two properties of graphene.

(S,conducts)

A

strong, conducts electricity

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15
Q

What is a fullerene?

(H cage, of C Atoms, sphere, or tube)

A

hollow cage of carbon atoms arranged as a sphere or a tube

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16
Q

What is a nanotube?

(H cylinder, C A)

A

hollow cylinder of carbon atoms

17
Q

Give two properties of nanotubes.

(H tensile S, conduct)

A

high tensile strength, conduct electricity

18
Q

Give three uses of fullerenes.

Lbrcnts, drg dlvry(spheres), H tech E

A

lubricants, drug delivery (spheres), high-tech electronics

19
Q

what is an ion?

A

atom that has lost or gained electrons

20
Q

Which kinds of elements form ionic bonds?

A

metals and non-metals

21
Q

What charges do ions from Groups 1 and 2 form?

A

Group 1 forms 1+, Group 2 forms 2+

22
Q

What charges do ions from Groups 6 and 7 form?

A

Group 6 forms 2−, Group 7 forms 1−

23
Q

Describe the structure of a giant ionic lattice.

(regular S, alternating P and N ions, together, electrostatic F, attraction)

A

regular structure of alternating positive and negative ions, held together by the electrostatic force of attraction

24
Q

Why do ionic substances have high melting points?

(electrostatic attraction, P and N. stromg,energy)

A

electrostatic force of attraction between positive and negative ions is strong and requires lots of energy to break

25
Q

Why don’t ionic substances conduct electricity when solid?

(ions in F positions,move,N delocalised E)

A

ions are fixed in position so cannot move, and there are no delocalised electrons

26
Q

When can ionic substances conduct electricity?

when M or D

A

when melted or dissolved

27
Q

Why do ionic substances conduct electricity when melted or dissolved?

free to M, charge

A

ions are free to move and carry charge

28
Q

Describe the structure of a pure metal.

layers of P M ions, S delocalised E

A

layers of positive metal ions surrounded by delocalised electrons

29
Q

Describe the bonding in a pure metal.

(strong, metal I, D electrons)

A

strong electrostatic forces of attraction between metal ions and delocalised electrons

30
Q

What are four properties of pure metals

A
  • malleable
  • high melting/boiling points
  • good conductors of electricity
  • good conductors of thermal energy
31
Q

Explain why pure metals are malleable.

layers,slide

A

layers can slide over each other easily

32
Q

Explain why metals have high melting and boiling points.

EF of A, D electrons, strong, energy

A

electrostatic force of attraction between positive metal ions and delocalised electrons is strong and requires a lot of energy to break

33
Q

Why are metals good conductors of electricity and of thermal energy?

D electrons, free to move, metal

A

delocalised electrons are free to move through the metal

34
Q

What is an alloy?

mixture,metal,anothe element

A

mixture of a metal with atoms of another element

35
Q

Explain why alloys are harder than pure metals

(different sized A, D the L, Preventing, S over eachother)

A

different sized atoms disturb the layers, preventing them from sliding over each other

36
Q

How are nanomaterials different from bulk materials?

(H surface A-T-V ratio)

A

nanomaterials have a much higher surface area-tovolume ratio

37
Q

What is the relationship between side length and surface area-to-volume ratio?

(side length D, factor of T,surface A-T-V ratio, increases, by factor of T)

A

as side length decreases by a factor of ten, the surfacearea-to-volume ratio increases by a factor of ten

38
Q

What are nanoparticles used for?

( Hlthcre,elctrncs,csmtcs,ctalyst )

A

used in healthcare, electronics, cosmetics,
and catalysts

schewl >_< (23 decks)

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