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Chemistry 2021 > Matter (2.4) > Flashcards

Matter (2.4) Flashcards

1
Q

<p>Define the term elements (4)</p>

A

<p>-An element is a substance that cannot be broken down into two or more simpler substances by chemical means

- Simplest form of matter that exists
- Consists of only one type of atom - can join to form molecules
- Can exist as either atoms or molecules</p>

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2
Q

<p>Define the term compounds</p>

A

<p>-Consists of atoms of two or more different elements chemically bonded together

- Constituent elements cannot be separated by physical means, but by chemical means
- Chemical properties are different from those of its elements
- Physical properties are individual
- Energy often given out as chemical bonds are being made
- Composition cannot vary - bond in fixed ratio</p>

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3
Q

<p>Define the term mixtures</p>

A

<p>-Consists of two or more elements and/or compounds physically intermingled

- Component substances can be separated by physical means
- Chemical properties of each substance in the mixture stay the same</p>

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4
Q

<p>What is the difference between an element and compound?</p>

A

<p>An element is a substance that cannot be broken down into two or more simpler substances by chemical means whereas a compound consists of atoms of two or more different elements chemically bonded together</p>

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5
Q

<p>What is the difference between a homogeneous and heterogeneous mixture?</p>

A

<p>Homogeneous mixture is where two or more substances that form the mixture are evenly distributed, one cannot visually separate components whereas a heterogeneous mixture is where two or more substances that form a mixture are not evenly distributed, one can visually separate the components</p>

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6
Q

<p>Define the term alloy</p>

A

<p>Mixture of a metal with other metals or compound</p>

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7
Q

<p>Define the term ionic bonding</p>

A

<p>Bonding that takes place between metals and non-metals due to a transfer of valence electrons from the metal to the non-metals
</p>

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8
Q

<p>Define the term lattice</p>

A

<p>A lattice is a regular arrangement of alternating cations and anions</p>

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9
Q

<p>Define the term covalent bonds</p>

A

<p>A covalent bond is formed between non-metals by sharing valence electrons</p>

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10
Q

<p>What is the difference between homonuclear and heteronuclear molecules</p>

A

<p>Homonuclear molecules are molecules of elements that are made up of atoms of the same kind e.g. F2,I2 whereas heteronuclear molecules are molecules of compounds that are made up of atoms of different kinds e.g. H2O, CO2</p>

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11
Q

<p>Define the term diatomic molecules</p>

A

<p>Molecules are made up of two atoms bonded together covalently, they can either be homonuclear or heteronuclear</p>

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12
Q

<p>What is the molecular shape of water?</p>

A

<p>V-shaped</p>

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13
Q

<p>What is the molecular shape of ammonia?</p>

A

<p>Pyramidal</p>

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14
Q

<p>What is the molecular shape of methane?</p>

A

<p>Tetrahedral</p>

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15
Q

<p>What is the molecular shape of carbon dioxide?</p>

A

<p>Linear</p>

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16
Q

<p>What is the difference between intermolecular and intramolecular forces</p>

A

<p>Intramolecular forces are the attractive forces between atoms within molecules or between ions within lattices. It is the bond that forms in ionic and covalent bonds whereas intermolecular forces are the attractive forces between molecules. It is the force responsiple for keeping molecules in a certain phase such as solids and liquids</p>

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17
Q

<p>What are giant covalent lattices?</p>

A

<p>Consists of a network of many repeating lattices of covalently bonded atoms</p>

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18
Q

<p>Define the term allotrope</p>

A

<p>Allotropes are formed when an element has more than one structure
Diamonds and graphite are allotropes of carbon</p>

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19
Q

<p>Define the term polyatomic ions</p>

A

<p>polyatomic ions are ions that consist of two or more atoms covalently bonded</p>

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20
Q

Explain the kinetic particle theory

A
  1. All matter consists of tiny particles
  2. The particles possess energy and are in continuous motion
  3. There are spaces between the particles
  4. Forces of attraction and repulsion also exist between the particles
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21
Q

How are the particles arranged in solids, liquids and gases?

A

Solids: Definite, repetitive pattern. Ordered lattice
Liquids: No definite shape
Gases: No definite shape

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22
Q

How do the spaces between particles of solids, liquids and gases look?

A

Solids: very small spaces
Liquids: small spaces
Gases: large spaces

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23
Q

How strong are the forces between particles of solids, liquids and gases?

A

Solids: strong
Liquids: weaker
Gases: very weak

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24
Q

How does the movement of particles look in solids, liquids and gases?

A

Solids: vibrate in fixed positions
Liquids: slide past each other
Gases: move freely

25
Q

How much kinetic energy do solids, liquids and gases have?

A

Solids: least
Liquids: more
Gases: most

26
Q

How is the volume in solids, liquids and gases?

A

Solids: fixed
Liquids: fixed
Gases: not fixed

27
Q

What happens when a something increases in heat (melts, boils, evaporates)?

A
  • Particles absorb energy and as a result gain kinetic energy and speed up
  • Overcome forces between particles holding them together and move apart
  • Particles start moving more randomly
28
Q

What happens when something decreases in heat (freezes, condenses)?

A
  • Energy released
  • Particles lose kinetic energy and as a result slow down
  • As particles move closer together, the forces between particles become stronger
  • Particles move into more fixed shape
29
Q

Define the term diffusion

A

Process whereby particles in liquids and gases move from an area of high concentration to an area of low concentration.

30
Q

Name and explain the 2 factors that affect the rate of diffusion

A

Size of molecule – bigger molecules have greater molecular mass, so they need to absorb more kinetic energy to move and diffuse. Smaller molecules diffuse quicker than larger molecules

Temperature – temperature determines how much kinetic energy a molecule has. Higher temperature means more kinetic energy. Higher temperature = faster diffusion

31
Q

Define the term ion

A

Atom with an electrical charge due to the loss or gain of electrons

32
Q

What are isotopes?

A

Atoms of the same elements with the same number of protons, but different mass numbers due to different numbers of neutrons

33
Q

Define radioactive isotopes

A

Isotopes that release an unstable type of energy during radioactive decay

34
Q

Explain what radioactive decay is

A

When the nucleus splits up or decays and forms two or more different atoms with different atomic numbers to the original isotope

35
Q

What is transmutation?

A

A new element is formed when the nucleus decays

36
Q

Name the 4 uses of radioactive isotopes

A

Carbon-14 dating
Radiotherapy
Control thickness of materials
Power generation

37
Q

What are the physical properties of alkali metals?

A

Good conductors of heat and electricity
Soft – can be cut with knife
Low density – very light, they float on water
Low melting and boiling points

38
Q

Explain what happend to trends as we move down the group of alkali metals

A

Softness increases
Density increases
Melting and boiling points decrease
Reactivity increases – most reactive metal is at the bottom of the group

39
Q

Explain what happens to lithium, sodium and potassium when the react with water

A

When they react with water, they form soluble, soapy hydroxides (alkaline solution) and hydrogen.
Hydroxides cannot be precipitated

Lithium, Li, floats on water, fizzes slowly, and remains solid throughout
Sodium, Na, floats on water, fizzes quickly and melts into a ball
Potassium, K, floats on water, fizzes violently and bursts into a violet flame

40
Q

What colour are lithium, sodium and potassium’s flames after reacting with water?

A

Lithium: red
Sodium: orange
Potassium: voilet

41
Q

What are the physical properties of halogens?

A

Form coloured gases – fluorine is pale yellow, chlorine is green, bromine is red, iodine is dark brown/ black
Poisonous
Diatomic

42
Q

Explain what happens to trends as we move down the group of halogens

A

Colour gets deeper
Density increases
Boiling and melting points increase
Reactivity decreases – most reactive non-metal is at the top of the group
At room temperature state changes from a gas(fluorine and chlorine) to liquid(bromine) to solid(iodine).

43
Q

Why are halogens so reactive?

A

They need to only gain one electron to gain a full outer shell, so they have a strong drive to react with other elements and compounds.

44
Q

What are the properties of noble gases?

A

Non-metals
Colourless gases
Monoatomic
Unreactive – they have a full outer shell of electrons

45
Q

Explain what happens to trends as we move down the group of noble gases

A

Atoms increase in size and mass
Density increases
Boiling points increase

46
Q

Name the uses of noble gases

A

Helium – fill air balloons and airships, because it is lighter than air and unreactive
Argon – used in tungsten light bulbs
Neon – used un advertising signs because it glows red
Krypton – used in lasers
Xenon – gives light like a bright daylight with a blue tinge. Used in lighthouse lights, operating rooms and car headlights

47
Q

What are the physical properties of transition elements?

A 
Hard, tough and strong
High melting points
Malleable (can be hammered into shape without breaking)
Ductile (can be drawn into wires)
Good conductors of heat and electricity
High density – heavy
48
Q

What are the chemical properties of transition elements?

A 
Much less reactive than group 1 metals
No trend in reactivity
Form coloured compounds
Can form ions with different charges
Can form more than one compound with another element
Can form complex ions
Act as catalysts – speed up reactions
Used in making alloys
49
Q

Describe what the allotrope graphite looks like

A

Made of flat sheets of carbon
Each carbon bonds to three other carbons
This gives rings of 6 atoms
Sheets of atoms lie on top of each other

50
Q

What are the properties of graphite?

A

Soft and slippery – layers can slide over each other because of weak bonds between layers
Very high melting point – strong covalent bonds between the atoms
Can be used as lubricant or additive to oil
Good conductor of electricity – each atom has four outer electrons, but only three bonds. The fourth electron is free to carry charges

51
Q

Describe what diamond looks like

A

Each carbon covalently bonded to four other carbons in a tetrahedral shape to form a giant covalent structure.

52
Q

Describe what buckminsterfullerene looks like

A

Consists of only carbon atoms covalently bonded together
60 carbon atoms bonded together to form the shape of a football
20 hexagons and 12 pentagons
Each carbon atom has 3 bonds
Homonuclear molecule
Buckyball
Drug-delivery systems, lubricants and catalysts

53
Q

What are the properties of diamond?

A

Very hard – each atom held in place by four strong bonds in rigid tetrahedral structure. Therefore it is used in cutting
Very high melting point – strong covalent bonds between atoms
Cannot conduct electricity – no free ions or electrons to carry charges

54
Q

Describe silicon dioxide

A

Main constituent of sand
Same tetrahedral structure as diamond
Melting point very high due to strong covalent bonds between atoms
Formula is SiO2. One silicon atom is bonded to four oxygen atoms, but one oxygen atom is shared between two silicon atoms.
Same properties as diamond, but slightly weaker covalent bonds.

55
Q

Describe the term metallic bonding

A

Lattice of positive ions in a ‘sea’ of delocalised electrons

56
Q

What are the physical properties of metals?

A

Are malleable – they can be hammered or pressed into sheets without breaking
Are sonorous – make a ringing sound when hit
Are ductile – they can be drawn into wires
Have high densities (except aluminium, magnesium and alkali metals)
Have high melting points
Are solids at room temperature (except mercury which is a liquid)
Are shiny

57
Q

Why are metals conductors?

A

The free electrons can carry heat and charges

58
Q

Why are metals malleable and ductile?

A

The rows of positive metal ions can slide over each other

59
Q

Why do metals have a high melting point/are solids?

A

The strong metallic bond requires a lot of energy to be broken

Chemistry 2021 (4 decks)

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