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Yr 11 Chemistry > U1- Bonding and shapes > Flashcards

U1- Bonding and shapes Flashcards

1
Q

metallic bond

A

a lattice of positively charged ions (cations) surrounded by free-moving ‘delocalised’electrons

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2
Q

metals are good conductors of heat because

A

the fact that they have delocalised electrons flowing through the lattice which can collide with the metal ions and pass on heat energy

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3
Q

metals are good conductors of electricity because

A

sea of delocalised electrons flowing through the lattice are free to move and carry electrical charge

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4
Q

metals are malleable and ductile because

A

the fact that the attraction between the metal lattice and delocalised electrons can take a fair amount of force before the lattice breaks and so it maintains its properties whilst changing shape

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5
Q

metals generally have high melting and boiling points because

A

the fact that the electrostatic force of attraction between the metals cations and the delocalised electrons is strong and requires a lot of energy to break

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6
Q

alloys

A

combinations of two or more metals

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7
Q

alloys vs pure metals

A

because when two or more metals form an alloy, the arrangement of the ions is disturbed tf alloys are:
harder than pure metals
less malleable
poorer conductors

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8
Q

metals are lustrous because

A

delocalised electrons form a barrier to reflect the light from the surface

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9
Q

galvanising/ galvanisation

A

the process of applying a protective zinc coating to steel or iron to prevent rusting

protects iron or steel by preventing corrosive substances from reaching the underlying steel/iron and protects iron by corroding first

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10
Q

extraction of iron

A

1) coke reacts in oxygen to form carbon dioxide
C + O2 –> CO2
2) CO2 is reduced by carbon to form carbon monoxide
CO2 + C –> 2CO
3) CO reduces iron oxide to form iron
Fe2O3 + 3CO –> 2Fe + 3CO2
4) Limestone breaks down in heat calcium oxide ad carbon dioxide
CaCO3 –> CaO + CO2
5) calcium oxide reacts with sand to form slag
CaO + SiO2 –> CaSiO3

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11
Q

extraction of aluminium

A

1) Bauxite is purified and crushed then dissolved in NaOH
2) Dissolved in cryolite (Na3AlF6) as this lowers the boiling point to 1000C compared to AL2O3 2040C boiling point
3) At cathode: Al3+ + 3e –> Al (red)
4) At anode: 2O2 –> O2 + 4e (ox)
5) Then at anode (as anode made of C):
C + O2 –> CO2
so anode needs replacing

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12
Q

formula unit

A

smallest whole number ratio of atoms in an ionic compound

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13
Q

why do atoms gain or lose electrons?

A

to form a stable configuration

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14
Q 
polyatomic ions symbol for:
acetate (ethanoate)
permanganate
cyanide
chromate
dichromate
peroxide
A 
CH3COO-1
MnO4-1
CN-1
CrO4-2
Cr2O7-2
H2O2
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15
Q

*molecular formular

A

smallest unit of a substrate that retains the chemical and physical properties of a substrate.
they have a known formula
2 or > non metals

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16
Q

covalent bond

A

shared pair of electrons between. two non-metallic atoms

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17
Q

dative covalent bond

A

covalent bond in which both of the shared electrons are contributed by one atom only
eg NH4

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18
Q

valence structure vs lewis structure

A 
valence = lone pairs have dots, bonds have lines
lewis = all dots
19
Q

octet rule

A

covalent bonds form so that the bonded atoms obtain a noble gas configuration generally having 8 e- in outer shell
(hw) not always true eg boron or sulfur

20
Q

Valence Shell Electron Pair Repulsion (VSEPR) Theory

A

electron pairs within a molecule have a repulsive effect on each other
shape of a molecule is determined by the number of electron pairs surrounding the central atom
shape affects melting point, boiling point, hardness and solubility
(double bond pair behaves as a single region of electron density)
(lone pair is more repulsive than bonding pair)

21
Q

shape: linear

A

4 total e-
2 bp
0lp

OR

3 lp

22
Q

shape: trigonal planar

A

6 total e-
3 bp
0lp

23
Q

shape: tetrahedral

A

8 total e-
4 bp
0 lp

24
Q

shape: trigonal bipyramidal

A

10 total e-
5 bp
0 lp

25
Q

shape: octahedral

A

12 total e-
6 bp
0 lp

26
Q

shape: pyramidal

A

8 total e-
3 bp
1 lp

27
Q

shape: bent

A

8 total e-
2 bp
2 lp

28
Q

buckyballs

A

allotrope of carbon

C60 soccer balls- spherical arrangement of hexagons and pentagons

29
Q

diamond properties

A

giant lattice structure
tetrahedral arrangement
strong covalent bonds
can’t conduct electricity

30
Q

SiO2 properties

A

tetrahedral arrangement
high melting point
X conduct electricity

31
Q

Graphite properties

A

C bonded to 3 C
high melting point- bc strong covalent bonds require lots of nrg 2 break
insoluble in water
conduct electricity- spare e becomes delocalised bw layers and r able to carry electrical charge
hexagonal layers
soft- layers can slide over each other (dispersion forces bw layers)

32
Q

carbon nanotubes

A

semiconductors in electrical circuits
act as a component of industrial catalysts
fibres are v strong tf used in ‘composite materials’
can cage other molecules

33
Q

by what angle does each lone pair reduce the bond angle?

A

2.5 degrees. default is 109.5 degrees

34
Q

intramolecular forces

A

bonds within the elements

eg covalent, ionic, metallic

35
Q

properties of covalent molecules

A

low melting and boiling point
can’t conduct electricity excluding water
low solubility in water

36
Q

diamond properties + explanation

A

C allotrope w ea C covalently bonded to 4 C –> tetrahedral shape
Strong covalent bonds
high melting point bc strong c bonds require lots of nrg to break
X conduct elect bc no delocalised e that can carry elect charge
insoluble in water
hard

37
Q

SiO2 properties

A

tetrahedral shape
high melting point bc strong covalent bonds require lots of nrg 2 break
X conduct elect bc no delocalised e can carry a charge
insoluble in water
hard

38
Q

dispersion forces

A

temporary fluctuating dipoles caused by the constant movement of electrons giving rise to electrostatic forces of attraction
bigger molecule, greater SA tf stronger dispersion forces
more electrons in a sample, a greater di[pole can exist tf greater strength of dispersion force

39
Q

polar

A

an uneven distribution of charge

40
Q

dipole dipole

A

permanent dipole

occurs bw polar molecules (if intermolecular bonds are polar and shape= asymmetrical)

41
Q

hydrogen bonding

A

extra strong dipole dipole attraction between molecules with hydrogen bonded to a NOF and attracted to a NOF

42
Q

what makes a bond more polar

A

the larger the difference in electronegativity the more polar a molecule is (the further they are from each other in the periodic table).
most electronegative= top right Fluorine
least electronegative= bottom left Caesium

43
Q

valence structure (drawing)

A

lines for shared pairs, dots for lone pairs

44
Q

lewis structure

A

dots for ALL electrons

Yr 11 Chemistry (12 decks)

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