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Chemistry 1/2 > Unit 1 Exam Revision > Flashcards

Unit 1 Exam Revision Flashcards

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1
Q

Proton

A

A positively charged particle that is inside the atomic nucleus of an atom.

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2
Q

Electron

A

It is a negatively charged particle and they obit around the nucleus of an atom.

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3
Q

Neutron

A

They do not contain a charge. They are situated inside the nucleus with protons.

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4
Q

Mass number

A

The number of protons and neutrons in the nucleus of an atom. Also called nucleons.

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5
Q

Atomic number

A

The number of protons or electrons in the nucleus of an atom.

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6
Q

Isotope

A

Atoms with the same atomic number but different mass numbers (different number of neutrons).

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7
Q

Electron configuration

A

Electrons are found in shells around the nucleus of an atom. The different energy levels or shells can hold a different number of electrons.

Number of subshells within a shell = n
Number of orbitals within a shell = n2
Number of electrons within a shell = 2n2

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8
Q

Formation of ions

A

Ions form when atoms gain or lose electrons. The most common ion of an atom is formed when an atom gains/loses electrons to form a complete outer shell.

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9
Q

Exceptions

A

A few elements have electrons configurations that do not follow the normal pattern.
Cr and Cu are exceptions as their electron configuration is different to the standard rule of filling. Their electron configurations are:

Cr: 1s2 2s2 2p6 3s2 3p6 3d5 4s1

Cu: 1s2 2s2 2p6 3s2 3p6 3d10 4s1

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10
Q

Orbitals

A
  • The s subshell contains 1 orbital
  • The p subshell contain 3 orbitals
  • The d subshell contains 5 orbitals
  • The f subshell contains 7 orbitals
  • The g subshell contains 9 orbitals
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11
Q

Groups

A

Column number indicated groups. Elements in the same column have the same number of electrons in the outer shell.

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12
Q

Periods

A

Row number indicates periods. Elements found in the same row have the same number of electron occupied shells.

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13
Q

Blocks

A

There are 4 different blocks in the periodic table. There is the S block, D block, P block and F block.
S block: Alkali and alkaline earth metals
D block: transition mental
P block: halogens, noble gases and metalloids
F block: lanthanides and actinides

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14
Q

Group 1

A

Alkali metals – form ionic compounds, very reactive metals with oxygen and water, low electronegativities, powerful reactants (lose electrons), relatively soft metal.

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15
Q

Group 2

A

Alkaline earth metals - form ionic compounds, reactive metals, low electronegativities, strong reactants.

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16
Q

Group 17

A

Halogens – reactive non-metals, form ionic and covalent compounds, high electronegativities, powerful oxidants (gain electrons)

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17
Q

Group 18

A

Noble gases – unreactive gases however a few compounds of krypton, xenon and radon have been made; outer shell contains 8 electrons except Helium.

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18
Q

Metallic character (groups)

A
  • INCREASES
  • The atomic radius of each successive atom increases, the forces of attraction between the core and the valance electrons decreases, the outer shell electrons are less strongly bonded making it easier for an atom to lose electrons.
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19
Q

First ionisation energy (group)

A
  • DECREASES
  • The atomic radius of each atom increases. The force of attraction between the core and the valance electrons decrease, making it easier for the atom to lose electrons.
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20
Q

Atomic size (group)

A
  • INCREASES
  • As electrons are filling shells that are located further from the nucleus, the atomic radius of each element increases. The more electrons, the bigger the atom.
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21
Q

Electronegativity (group)

A
  • DECREASES
  • The number of electrons occupies shells increases, hence the atomic radius of each atom increases, the outer shell electrons are further away from the nucleus, and they are attracted more weakly.
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22
Q

Metallic character (period)

A
  • DECREASES
  • As the core charge increases, the electrons are held more tightly, that is the nucleus has a stronger attraction to the outer shell electrons and atoms are less able to release electrons and form positive ions.
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23
Q

first ionisation energy (period)

A
  • INCREASES
  • The core charge and valence shell charge increases and the atomic radii decreases. The attractive forces between the core and valence electrons increases, making it more difficult for an atom to lose electrons.
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24
Q

Atomic size (period)

A
  • DECREASES
  • The electrons are being added to the same shell, so the effect of the increasing nuclear charge on the outermost electron is to pull them closer to the nucleus. The increasing core charge pulls the outermost electrons closer to causing the atomic size to decrease.
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25
Q

Electronegativity (period)

A
  • INCREASES
  • The atomic radius of each atom decreases resulting in stronger attractive forces between the two entities. This makes it easier for an atom to attract an electron from another atom, and hence the electronegativity increases.
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26
Q

relative atomic mass formula

A

The relative atomic mass (RAM or Ar) of an element is the average of the masses of the naturally occurring isotopes each weighted according to its abundance.

Ar (x) = [(RIM x %Ab)1 + (RIM x %Ab)2 ] Divide by 100

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27
Q

Relative abundance

A

Let x = percentage abundance 1
100-x = percentage abundance 2

Ar (e.g Ga) = (RIM x %Ab)1 + (RIM x %Ab)2
69.74 = (69/1 x x/100) + (71/1 x 100-x/100)
6974 = 69x + 71(100-x)
Etc.

28
Q

Percentage composition

A

Percentage composition is the percentage that each element contributes to the total mass of a compound.

E.g. %Sn = Ar(Sn) x1 / Mr (SnFe2) x 100
It is x1 because there is one Sn atom.

29
Q

Empirical formula

A

Steps:

  1. Write down the symbols of the elements present
  2. Assume that the mass of the sample is 100g and so convert all percentages into grams
  3. Convert masses in moles
  4. Find the simplest whole number ratio of the atoms by dividing all numbers of moles by the smallest number of moles.
  5. If necessary, multiply by a factor to convert all numbers to whole numbers.
30
Q

Molecular formula

A

Empirical formula x n = molecular formula where n represents a whole number.

E.g. Benzene has the empirical formula CH and its molar mass is 78g/mol. Find the molecular mass.
Mr(CH)
12+1 = 13 
Mr(EF)x = Mr(MF)
13x = 78
X = 6
(CH) x 6 = C6H6
31
Q

Lustrous (metal)

A

The presence of delocalised electrons at the surface of the metal causes most of them to be reflectors of visible light when cut or polished.

32
Q

Conductors of electricity (metal)

A

All metals are electrical conductors as the delocalised electrons in a metallic lattice are free to move.

33
Q

Conductors of heat (metal)

A

Metals contain particles which are very mobile -> free moving particles. As the temperature of a metal increases, the vibration of the ion in their fixed lattice becomes increasingly more violent. Thus, the conductivity of metals decreases with increasing temperature.

34
Q

Melting and boiling point (in metals)

A

Strong forces of attraction exist between particles. Large amounts of thermal energy are required to break the bond between positive ions and the delocalised electrons.

35
Q

Dense (metal)

A

The particles in metals are packed closely together. The denser the metal the higher the melting point. Density depends on the mass and volume of the individual ions and how closely they are packed together in each crystal.

36
Q

Malleable and ductile (metal)

A

Metals can be hammered, bent or rolled into any shape or drawn out into wires. Layers of atoms can move past one another without disrupting the fore between the positive ions and the negative sea of electrons.

37
Q

Tensile strength (metal)

A

Tensile strength is the ability to withstand a stretching force. This will be greater, the stronger the forces drawing the particles together.

38
Q

Hardness (in metals)

A

It is a measure of how difficult it is to scratch. In order to scratch a substance, the particles in the surface layers where the scratch occurs must be shifted out of their position. The stronger the bonds, the harder it is to scratch.

39
Q

Transition metals in comparison to group 1 and 2

A
  • Atoms tend to be smaller
  • They show higher melting and boiling points
  • Tend to be harder
  • High tensile strength and good mechanical properties
    This is because across the periodic table, core charge increases and atomic radius decreases.
40
Q

Modifying metals

A

Pure metals are not always the best choice for most applications. They may corrode too easily, or be too brittle, or too soft, or have low tensile strength or shoe metal fatigue too readily.

41
Q

Generally crystalline (ionic compound)

A

Solids of ionic compounds are generally crystalline due to the regular array of ions.

42
Q

Conduct electricity in a molten or aqueous state (ionic compound)

A

Ions are held in the crystal lattice and are not free to move. There are no free ions or electrons to conduct electricity. When melted or dissolved in water, the ions are no longer fixed in the lattice and are free to move.

43
Q

Hard (ionic compounds)

A

The crystals are very hard due to the strong ionic bonds.

44
Q

High MP and BP (ionic compounds)

A

The crystals have high melting and boiling points due to the strong bonding in 3 dimensions.

45
Q

Brittle (ionic compound)

A

The highly directional bonding prevents salt crystals from being bendable or malleable like metal. Ionic compounds are brittle since breaking one bond results in all the bonds in one plane also breaking. Distortion of an ionic crystal causes the ions of the like charges to come close together and repulsion between these ions cleaves or shatters the crystal.

46
Q

Naming ionic compounds

A
  1. The first element (metal cation) in the formula is named in full
  2. The second element is named as an anion. The name is shortened and given an –ide suffix.
47
Q

hydrated ionic compounds

A

A number of ionic compounds, called hydrates, produce water when they decompose upon heating. When a formula of a hydrated compound is written, the number of water molecules is also included.

48
Q

Low MP and BP (molecular)

A

Weak forces between molecules therefore relatively little energy is required to break these forces.

49
Q

Soft solids (molecular)

A

The molecules are only weakly attracted to each other and are easily displaced.

50
Q

Non- conductors of electricity (molecular)

A

No mobile charged particles; the molecules are not charged. All of the electrons within a molecule are either tightly bound to the atom or are shared by the atom in covalent bonds.

51
Q

Solubility in water and other solvents (molecular)

A

Polar molecules are soluble in polar solvents.

Non-polar molecules are soluble in non-polar solvents.

52
Q

High melting temp (covalent network)

A

Covalent bonds are very strong therefore very high temperatures are required to provide the heat energy needed to break the covalent bonds.

53
Q

Hard (covalent network)

A

Covalent bonds are very strong therefore very high temperatures are required to provide the heat energy needed to break the covalent bonds.

54
Q

Chemically inert (covalent network)

A

Covalent bonds are very strong therefore very high temperatures are required to provide the heat energy needed to break the covalent bonds.

55
Q

Brittle (covalent network)

A

Atoms cannot move relative to one another without disrupting the directional covalent bonds that hold them together. A strong deforming force shatters the crystal.

56
Q

Do not conduct electricity (covalent network)

A

No ion, all valence electrons are localised in the covalent bond therefore a non-conductor of electricity.

57
Q

High melting temp (covalent layer)

A

Strong covalent bonds between carbon atoms within the layer.

58
Q

Soft, flaky material (covalent layer)

A

Weak dispersion forces between planes are easily overcome by a force applied parallel to them. Layers of atoms can be made to slide over one another.

59
Q

Good conductor of electricity (covalent layer)

A

Delocalised electrons can move across the sheets under the influence of an applied electric field.

60
Q

Black, opaque appearance (covalent layer)

A

Delocalised electrons are able to absorb visible light.

61
Q

Less dense than diamond (covalent layer)

A

Less atoms per unit of volume due to structural arrangement

62
Q

Intramolecular forces

A

Single covalent bond
Double covalent bond
Triple covalent bond

63
Q

Intermolecular

A

Dispersion forces -> every bond contains it
Hydrogen bonds -> Only occurs when hydrogen binds to either: F, O or N
Dipole – dipole -> When a hydrogen bond does not occur

64
Q

Naming covalent molecules

A 
The first element remains the same but the second element gets the suffix of –ide. 
The first element gets a prefix unless there is only one molecule. The second element also gets a prefix:
Mono = 1
Di = 2
Tri = 3
Tetra = 4
Penta = 5
Hexa = 6
Hepta = 7
Octa = 8
Nona = 9
Deca = 10
65
Q

Giant structures

A

Some non-metals form giant structures in which no individual molecule exists. They consist of countless numbers of atoms covalently bonded together. Elemental carbon occurs in teo allotropic forms, diamond (network lattice) and graphite (layer lattice)

Chemistry 1/2 (2 decks)

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