7H - Atoms, molecules, elements and compounds Flashcards

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1
Q

What is a molecule?

A

More than one atom bonded together.

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2
Q

What are mixtures?

A

Materials that contain more than one substance which are NOT joined together.

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3
Q

What happens if a natural material is pure?

A

Contains only one substance (isn’t mixed).

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4
Q

What are elements?

A

Substances made out of only one type of atom.

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5
Q

What are compounds?

A

Substances made out of more than one kind of atom (element) bonded together.

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6
Q

What is O?

A

Oxygen

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7
Q

What is Mg?

A

Magnesium

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8
Q

What is Fe?

A

Iron

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9
Q

What is Si?

A

Silicon

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10
Q

Where do we obtain all the elemnts and compounds we need from?

A

From the earth’s atmosphere and crust.

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11
Q

Why is it important to recycle?

A

Because our resources are limited and some may run out in the near future.

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12
Q

What are the 5 common properties of metals?

A
  • High melting point
  • Strong and flexible
  • Shiny
  • Good conductors of heat
  • Good conductors of electricity
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13
Q

What are the 5 common properties of non metals?

A
  • Low melting points
  • Brittle
  • Not shiny
  • Poor conductors of heat
  • Poor conductors of electricity
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14
Q

What determines the uses of a material?

A

Its properties.

i.e. copper is strong, flexible and conducts electricity so its used for electricity cables.

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15
Q

What is the name of the only liquid metal?

A

Mercury

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16
Q

What is the first name of a compound if there’s a metal present?

A

The name of the metal

17
Q

What is the second name of a compound with only two elements?

A

one element name has its name ending changed to -ide

(i.e. sodium + chlorine = sodium chloride)

18
Q

If a compound contains two elements plus oxygen, what is its second name?

A

The name of an element with its ending changed to -ate.

(i.e. magnesium + nitrogen + oxygen = magnesium nitrate)

19
Q

What do chemical reactions always form?

A

New substances

20
Q

What are the typical signs of a chemical reaction taking place?

A
  • Colour change
  • Gas given off
  • Solid being formed
  • An energy change
21
Q

If a chemical reaction doesn’t need heat to continue reacting, does it need heat to start reacting?

A

Some reactions need heat to start, but once started they give off heat.

(i.e. burning petrol)

22
Q

Do all reactions need heat to start?

A

No. some just start reacting by getting mixed.

(i.e. acids and alkalis)

23
Q

Name a reaction that needs a continuous supply of energy (heat) to keep on going.

A

Breaking down metal ores

24
Q

Give examples of chemical reactions

A

Burning, cooking, rusting, digesting food.

25
Q

What happens during thermal decomposition reactions?

A

A single compound is broken down using heat.

(i.e. Tin carbonate > tin oxide + carbon dioxide)

26
Q

What is the word equation for the thermal decomposition of copper carbonate?

A

Copper carbonate > copper oxide + carbon dioxide

27
Q

What is the main use of thermal decomposition reactions?

A

used in industry to extract metals from metal ores.

28
Q

What is the percentage of nitrogen in air?

A

78%

29
Q

What is the percentage of oxygen in air?

A

21%

30
Q

What is the percentage of ‘other’ gases that aren’t oxygen or nitrogen in air?

A

1%

31
Q
A