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a level chemistry ocr a > Idk > Flashcards

Idk Flashcards

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1
Q

Ionic bonding

A

Square

Electrostatic attraction between oppositely charged ions

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2
Q

Covalent

A

Circles joined

Electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms

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3
Q

Polar

A

Difference in electronegativity, dipoles dont cancel out

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4
Q

How London forces appear

A

Electrons in an atom are constantly moving

Electrons can become unevenly distributed, creating a slightly negative charge

This creates a slightly positive charge in neighbouring molecule

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5
Q

Ionisation energy down groups

A

First ionisation energy decreases

Atomic radius increases

More inner shells so shielding increases

Nuclear attraction on outer electrons decreases

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6
Q

Ionisation energy across periods

A

First ionisation energy increases

Atomic radius decreases

Nuclear charge increases

Electrons on same shell so, similar shielding

Nuclear attraction increases

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7
Q

Ionisation energy across periods exception

A

Boron - single electron in 2p sub shell

Oxygen - electrons are paired in first p orbital. Electrons repel making it easier to lose the electron

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8
Q

Boron, carbon, silicon

A

Giant covalent lattices

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9
Q

Carbon

A

Each carbon atom forms 4 strong covalent bonds

Insoluble

Doesn’t conduct electricity

High MP&BP

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10
Q

Graphite

A

Each carbon atom forms 3 strong covalent bonds meaning, 1 delocalised electron

No bonds between layers so soft

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11
Q

Group 2

A

Ionisation energy decreases down group

Nuclear attraction decreases due to increasing atomic radius & increased shielding

Reactivity increases down group

Solubility & pH also increase

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12
Q

Group 7

A

Diatomic, BP increases down group due to stronger London forces

Reactivity decreases as less nuclear attraction so harder to gain electron

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13
Q

Chlorine - colour in solution, colour in cyclohexane, precipitate dissolves in

A

Pale green
Pale green
Dilute ammonia

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14
Q

Bromine - colour in solution, colour in cyclohexane, precipitate dissolves in

A

Orange
Orange
Concentration ammonia

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15
Q

Iodine - colour in solution, colour in cyclohexane, precipitate dissolves in

A

Brown
Violet
Doesn’t dissolve

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16
Q

Disproportionation

A

Element is simultaneously oxidised & reduced

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17
Q

Relative atomic mass

A

Weighted mean mass of an atom of an element compared to 1/12th of the mass of an atom of carbon-12

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18
Q

Two anomalous properties of ice caused by hydrogen bonding

A

Ice is less dense than water due to the hydrogen bonding creating an open lattice

Ice also has a higher melting & boiling point as it contains hydrogen bonding which requires more energy to overcome

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19
Q

Explain why successive ionisation energies always increase

A

As each electron is removed, the outer shell is drawn closer to the nucleus.

Nuclear attraction is greater and more energy is needed to remove the next electron

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20
Q

Explain why Al has a lower first ionisation energy than Mg

Explain why S has a lower first ionisation energy than P

A

3p subshell in Al has a higher energy level than the 3s subshell in Mg. 3p electron is easier to remove.

P has 3 electrons in 3p subshell, 1 electron in each 3p orbital. S has 4 electrons in 3p subshell, 2 electrons paired in 1 orbital and 1 electron in other 2 3p orbitals.

Paired electrons in sulfur repel one another making it easier to remove one of those electrons

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21
Q

Properties of ionic compounds

A

Giant ionic lattice

High M&BP as electrostatic force holding the ionic lattice together is strong & requires a lot of energy to overcome

Molten - can conduct electricity as there are mobile ions to carry a charge

Solid - ions in a fixed position.

Brittle - when the layers of alternating charges are distorted, like charges repel, breaking apart the lattice into fragments

Soluble - polar water molecules break down the lattice and surround each ion in solution

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22
Q

Electronegativity

A

Atoms ability to attract electrons towards itself in a covalent bond

Increases across a period as atomic radius decreases & nuclear charge increases

Decreases down a group as shielding increases and atomic radius increases so nuclear charge decreases

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23
Q

Simple molecular

A

Definite molecular formula, Non & non

Simple molecular lattice

Molecules are held in place by weak intermolecular forces

Atoms within each molecule are bonded together strongly by covalent bonds

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24
Q

Properties of simple molecular

A

Weak intermolecular forces broken by small amounts of energy

Low melting and boiling points

Covalent bonds don’t break when heated

No mobile particles to carry a charge

Insoluble in polar solvents
- intermolecular bonding within the polar solvent is too strong to be broken

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25
Q

Metal + acid

Metal + carbonate

A

Salt + hydrogen

Salt + carbon dioxide + hydrogen

26
Q

Metal + water

A

Metal hydroxide + hydrogen

27
Q

Potential errors in using a gas syringe

A

Gas escapes before bung inserted

Some gases are soluble in water so true amount of gas is not measured

28
Q

Relative isotopic mass

A

Mass of 1 atom of an isotope relative to 1/12th of the mass of 1 atom of carbon-12

29
Q

Relative molecular mass

A

Mass of a molecule of the compound relative to 1/12 of the mass of one atom of carbon-12

30
Q

Molar mass

A

Mass in grams of 1 mole of a substance

31
Q

Empirical formula

Molecular formula

A

Simplest whole number ratio of atoms of each element in the compound

Actual number of atoms of each element in the compound

32
Q

Noble gases

A

Stable electron configuration

Full outer shell so, very stable

Monatomic - individual atoms with very weak forces between them

33
Q

Dative bonding

A

One of the atoms supplies both the shared electrons for the covalent bond

34
Q

Average bond enthalpy

A

Energy needed to break one mole of a particular bond, larger the bond, the stronger the covalent bond

35
Q

Giant covalent substances

A

Si, SiO2, diamond, graphite, graphene

36
Q

Isoelectronic

A

Same electrons

37
Q

Periodicity

A

Repeating pattern of properties shown across different periods within their position in the periodic table

38
Q

Using graph

A

Electrons in outer shell = lowest group of crosses

Period number = number of groups

39
Q

Atomic radius

A

Distance from nucleus to outer electron shell

40
Q

Electron shielding

A

Amount of shells

Lessen electron repulsion

41
Q

Nuclear charge

A

Protons in nucleus

42
Q

Melting point down group 2

A

Decreases down the group

Weaker metallic bonding

Metal ions have a larger ionic radius

So lower melting points

43
Q

Milk of magnesia

A
  • Mg(OH)2, neutralises acid (alkaline)
44
Q

Antacid

A

CaCO3, base, neutralises acid

45
Q

Slaked lime

A

Agriculture, Ca(OH)2, neutralises acidic soil

46
Q

Why does reactivity increase down the group

A

First ionisation energy decreases; less energy required to remove an electron

Atomic radius increases

More inner shells, electron shielding increases

Nuclear attraction decreases

47
Q

Identify metal

A

Mol = vol /24

Mol = gram / RAM

48
Q

Explain how this enables chemists to predict the shape

A

Pairs of electrons repel

Shape is determined by number of lone and bond pairs

49
Q

First ionisation energy of oxygen is less than fluorines

A

Oxygen has a higher atomic radius

Smaller nuclear charge

Weaker nuclear attraction

50
Q

Sulfate (IV)

A

SO3 2-

51
Q

Reactivity decreases down group 7

A

F A M N

First ionisation energy decreases

Atomic radius increases

More inner shells so more shielding

Nuclear attraction decreases

52
Q

Chlorine

A

Kills bacteria

Toxic

53
Q

Test for halide ions

A

React with acidified silver nitrate solution to form silver halide precipitates

Forms a white precipitate

54
Q

Alkalis

A

Release OH- ions in an aqueous solution

55
Q

Explain the differences in the melting points of phosphorus and chlorine

P4
Cl2

A

Phosphorus has more electrons

So, stronger Van Der Waals

More energy needed to overcome

56
Q

CO2 + H2O

A

CO3 2- and H+

57
Q

NH

A

NH4+ and NaOH

58
Q

Strong acid

A

Completely dissociates in aqueous solutions

59
Q

Weak acid

A

Partially dissociates in aqueous solutions

60
Q

Cl & Br

A

Orange due to Br

61
Q

I & Cl

A

Violet due to I2

62
Q

I % Br2

A

Violet due to I2

a level chemistry ocr a (26 decks)

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