The Chemical Earth Flashcards

1
Q

1.2

Identify the difference between elements, compounds and mixtures in terms of particle theory

A

Elements: all atoms are the same, properties are always the same
Compounds: contains identical clusters of two or more different atoms
Mixtures: ingredients retain properties and can be separated

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2
Q

1.3

Identify mixtures, elements and compounds in earth’s spheres

A

Biosphere: Nucleic acids, fats
Lithosphere: free elements (gold, platinum), minerals
Atmosphere: mixture of gases
Hydrosphere: water, dissolved sea salts

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3
Q

1.4

Identify and describe procedure and property that separates solids of different sizes

A

Sieving

Difference in particle size

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4
Q

1.4

Identify and describe procedure and property that separates dissolved solids in liquids

A

Evaporation

Different boiling points

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5
Q

1.4

Identify and describe procedure and property that separates solids and liquids

A

Filtration

Difference in particle size

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6
Q

1.4

Identify and describe procedure and property that separates liquids

A

Decantation

Density

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7
Q

1.4

Identify and describe procedure and property that separates gases

A

Distillation

Boiling points

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8
Q

1.5

What is gravimetric analysis and why is it needed?

A

It is used to determine quantities by mass of substances present in a sample.
The parts are labelled as percentage compositions

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9
Q

2.1

What is the relationship between reactivity of an element and the likeliness of it being found naturally uncombined?

A

The more reactive an element is, the less likely it is to be found naturally uncombined.

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10
Q

2.2

What are the main properties of metals?

A

Lustrous, high conductivity and density

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11
Q

2.2

What are the main properties of semi-metals?

A

Low sheen, moderately dense and malleable, high thermal conductivity, low electrical conductivity (semi-conductor), high boiling point

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12
Q

2.2

What are the properties of non-metals?

A

Dull, low thermal conductivity, no electrical conductivity, low density and boiling point

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13
Q

2.3

Account for uses of metals in terms of physical properties

A

Metal e.g. Aluminium

Use for foil, cans, saucepans, roofing, because of lustre, malleability, corrosion-resistance

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14
Q

2.3

Account for uses of non-metals in terms of physical properties

A

They have a large range of properties, so have various uses

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15
Q

2.3

Account for uses of semi-metals in terms of physical properties

A

Also vary greatly - conductivity increased by liquids such as As or B

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16
Q

3.1

Describe the interaction of particles in solids

A

Particles are in a fixed position and are close together, but still slightly vibrate

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17
Q

3.1

Describe the interaction of particles in liquids

A

Particles roll over each other, change formation, but stay attached

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18
Q

3.1

Describe the interaction of particles in gases

A

Particles have large spaces between them, move a lot and diffuse easily.

19
Q

3.2

Describe qualitatively the energy levels of electrons in atoms

A

Atoms have the same number of protons and electrons.

Energy levels in an atom increase as the amount of electrons in the shells increase.

20
Q

3.3

Describe atoms in terms of mass number and atomic number

A

Mass number: depends on the number of protons and neutrons = protons + neutrons
Atomic number: the humber of protons in the nucleus of an atom, and the number of electrons in the shells
Mass number labelled at the top, atomic number at the bottom.

21
Q

3.4

Describe the formation of ions

A

Ions form from atoms gaining or losing electrons.
Atoms with almost full shells gain an electron and become negatively charged.
Atoms will almost empty outer shells lose electrons and become positively charged.

22
Q

3.5

Apply the Periodic Table to predict ions formed by elements

A

Coming from the left, the groups increase in positive charge (until 3)
Coming from the right, excluding Noble Gases, atoms increase in negative charge (until 3)

23
Q

3.6

What are lewis electron dot structures

A

Diagrams that show the sharing of outer-shell electrons.

24
Q

3.7

Describe the formation of ionic compounds in terms of attraction of opposite charge

A

Ionic bonds form when a cation and anion are attracted to each other.
They form with one metallic and one non-metallic element

25
Q

3.8

Describe molecules as particles which can move independently of each other

A

A molecule is the smallest unit of a substance that can move independently. This includes molecules of covalent bonds and monatomic molecules

26
Q

3.9

Distinguish between molecules containing one atom and molecules with more than one atom

A

Noble gases contain one atom

Gases cannot exist as single atoms, so form molecules such as O2

27
Q

3.10

Describe the formation of covalent molecules in terms of sharing of electrons

A

Formed between non-metallic elements.

Covalent molecules bond by sharing electrons to stabilise their outer shell.

28
Q

4.1

Identify the difference between physical and chemical changes

A

Physical: may include state change, but no rearranging of atoms and no new substances are made
Chemical: Formation of a new chemical substance, breaking of bonds

29
Q

4.2

Describe the difference between boiling and electrolysis

A

Boiling: changes state of water from liquid to gas (physical change)
Electrolysis: changes water into hydrogen and oxygen, requires a lot more energy (chemical change)

30
Q

4.3

What are the tree decomposition reactions and what do they do?

A

Thermal: decompose through heat e.g. CuCO3^ -> CuO + CO2
Electrolysis: decompose through electricity and attraction to poles
Photolysis: decompose through light e.g. 2AgBr -> 2Ag + Br2

31
Q

4.4

What is the relationship between energy needed to separate atoms and strength of their attraction?

A

The stronger the bond, or attraction, the more energy is needed to break the bonds.

32
Q

5.1

What is a physical property? examples

A

Properties that can be observed or measured without changing the chemical composition
e.g. texture, colour, odour, density, melting point, solubility.

33
Q

5.1

What is a chemical property? examples

A

Properties that become evident during or after a chemical reaction
e.g. heat of combustion, flammability, chemical stability

34
Q

5.2

Describe the physical properties of metallic bonding

A

Malleability : high
Melting and boiling point: high
Conductivity (solid): high
Conductivity (liquid): high

35
Q

5.2

Describe the physical properties of ionic bonding

A
Hardness: high
Malleability : brittle
Melting and boiling point: low
Conductivity (solid): low
Conductivity (liquid): low
36
Q

5.2

Describe the physical properties of covalent molecular bonding

A
Hardness: soft
Malleability : brittle
Melting and boiling point: low
Conductivity (solid): low
Conductivity (liquid): low
37
Q

5.2

Describe the physical properties of covalent network bonding

A
Hardness: very high
Malleability : brittle
Melting and boiling point: very high
Conductivity (solid): low
Conductivity (liquid): low
38
Q

5.3

Describe metallic bonding

A

Lattice of metal cations, surrounded and held together by sea of delocalised electrons

39
Q

5.3

Describe ionic bonding

A

3D lattice that is held together by positive and negative ions being attracted to each other - formed by the transfer of electrons. REPEATED

40
Q

5.3

Describe covalent bonding

A

Occur between non-metals. Intermolecular forces hold the molecules of the compound together.

41
Q

5.4

Describe metals as three-dimensional lattices of ions in a sea of electrons

A

Metal atoms all lose their outer shell electrons to become cations, and the electrons travel around the cations, not belonging to any one atom

42
Q

5.6

Explain why the formula for an ionic compound is an empirical formula

A

The simplest whole number ratio - there is no discrete number of atoms in a compound

43
Q

5.7

Identify common elements that exist as molecules

A

H2, F2, Cl2, O2, N2, P4, S8

44
Q

5.7

Identify some common elements that consist as covalent lattices

A

Carbon (diamond), carbon (graphite)