EDEXCEL GCSE Chemistry - Unit 2 - Topic 4

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When do ionic bonds form?
Ionic bonds form when a metal reacts with a non-metal.
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When do covalent bonds form?
Covalent bonds form between atoms of non-metal elements.
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What are the properties of metallic substances? (5 points)
(1) Metals are good conductors of heat and electricity and are solids at room temperature. (2) Metals are insoluble in water. (3) Metals are malleable. (4) The atoms in metals are held by metallic bonds. (5) All metals conduct electricity.
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What makes metals malleable?
The layers of positive ions in a metal can slide over each other if a large force is applied to a piece of metal. The ions are still held together by the sea of electrons, so the metal spreads out instead of breaking.
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Why do metals have high melting and boiling points?
Metal atoms are held together by strong metallic bonds and a lot of energy is needed to break these bonds.
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What are delocalised electrons?
Free electrons that can move around between ions in a metal or in the layers of graphite.
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How do electrons behave when a voltage is applied across a piece of metal?
The delocalised electrons move around randomly between the positive ions in all directions. If a voltage is applied across a piece of metal, the electrons start to drift in one direction. This movement is an electric current.
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What are two properties of transition metals?
(1) Most transition metals have high melting points and (2) form coloured compounds.
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Where are the alkali metals found in the periodic table?
In group 1.
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What are the physical properties of alkali metals?
They are solids at room temperature but they have low melting points. They are all soft metals and can all be cut with a knife. The atoms in the alkali metals are held together by metallic bonding.
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What are the first three alkali metals and their symbols?
1) Lithium, Li 2) Sodium, Na 3) Potassium, K
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What do alkali metals have in common?
They all have one electron in the outer shell and therefore they have similar properties.
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What happens when alkali metals react with water?
Lithium, sodium and potassium all react vigorously with water. Hydrogen gas bubbles off and, in the case of potassium, this burns with a lilac flame. The metal hydroxide is formed which is a strong alkali.
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What happens when alkali metals are added to water?
They float and skid across the surface. Hydrogen fizzes off and the alkali metal gradually disappears. A metal hydroxide is formed, which dissolves into water. The water becomes alkaline and turns green universal indicator purple.
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What happens to the reactivity of alkali metals as you go down the group?
The reactivity of the alkali metals increases down the group. Potassium reacts more vigorously than sodium and lithium is the least reactive.
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What flame colours represent the first three alkali metal ions?
1) Lithium ion = red 2) Sodium ion = orange 3) Potassium ion = lilac
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What is the general equation for the reaction of an alkali metal with water?
alkali metal + water --> metal hydroxide + hydrogen
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How can we test for hydrogen gas?
A lighted wooden splint makes a squeaky popping sound in a test tube of hydrogen.
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What happens when lithium is added to water?
Lithium moves slowly across the surface of the water and gradually gets smaller as it turns into lithium hydroxide and hydrogen.
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Give the symbol equation for the reaction of lithium with water.
2Li (s) + 2H2O (l) --> 2LiOH (aq) + H2 (g)
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What happens when sodium is added to water?
Sodium moves quickly across the surface. It melts and forms a ball, then rapidly gets smaller as it turns to sodium hydroxide and hydrogen.
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Give the symbol equation for the reaction of sodium with water.
2Na (s) + 2H2O (l) --> 2NaOH (aq) + H2 (g)
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What happens when potassium is added to water?
Potassium melts and moves very fast across the water. The hydrogen produced often catches fire. The flame is lilac because of the potassium present.
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Give the symbol equation for the reaction of potassium with water.
2K (s) + 2H2O (l) --> 2KOH (aq) + H2 (g)
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Where are the halogens found is the periodic table?
In group 7.
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Name the first four halogens, their state and colour.
1) Fluorine, gas, pale yellow 2) Chlorine, gas, pale green 3) Bromine, liquid, red/brown 4) Iodine, solid, grey
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What type of atoms are halogens?
The halogens are diatomic, so their formulas are F2, Cl2, Br2, I2
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What is the trend in the reactivity of the halogens?
Halogens get less reactive going down the periodic table from fluorine to iodine.
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What do halogens form when they react with hydrogen?
Halogens react with hydrogen to form hydrogen halides.
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How do halogens react with metals?
Halogens react with metals to form ionic compounds as the halogens take electrons from the metal.
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What happens in the reaction of a halogen with a metal?
In the reaction, the halogen becomes negatively charged because of the electrons it gains and the metal becomes positively charged because it has lost electrons to the halogen.
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Give both the word and symbol equation for the reaction of iron with bromine.
iron + bromine --> iron bromide 2Fe (s) + 3Br2 (l) --> 2FeBr3 (s)
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What is a halogen displacement reaction?
A more reactive halogen will displace a less reactive halogen from its compound in solution. This is called a displacement reaction.
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What do halogen compounds contain?
Halogen compounds contain halide ions. These are colourless, but halogen atoms are coloured.
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What happens when a halogen displacement reaction occurs?
When a displacement reaction occurs, there is a colour change because a different halogen is produced.
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Where are the noble gases found in the periodic table?
In group 0.
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What sort of gases are noble gases in group 0?
Noble gases are inert because they already have full outer electron shells. Therefore it is very difficult to make them react with anything.
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Name the first six noble gases and their symbols.
1) Helium, He 2) Neon, Ne 3) Argon, Ar 4) Krypton, Kr 5) Xenon, Xe 6) Radon, Rn
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What is the trend in the boiling point and density of the noble gases?
The boiling point and density of elements increase going down group 0 of the periodic table.
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What is helium used for?
Helium is used in balloons and airships. It is much less dense than air, so balloons filled with it float upwards.
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What is neon used for?
Neon is used in fluorescent lamps and advertising displays as it produces a red coloured light when electric current is passed through the tube under low pressure.
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What is argon used for?
Argon is used in light bulbs. The very thin metal filament inside the bulb would react with oxygen and burn away if the bulb were filled with air instead of argon. Argon stops the filament burning away because it is inert.
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What is krypton used for?
Used in lasers. Krypton lasers are used by surgeons to treat certain eye problems and to remove birthmarks.
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What is argon and helium used for?
Used in welding to form a blanket over the hot metal to stop it reacting with oxygen from the air.
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What is argon used for? (Fire extinguisher)
Argon is used in fire-extinguishing systems because it is non-flammable. Spaces such as computer server room can be filled with argon if a fire breaks out.
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When and how were the noble gases discovered?
The noble gases were discovered in 1894 as a result of observation, hypothesis and experimentation.
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What was the observation? (discovery of noble gases)
Nitrogen produced from the air had a different density from hydrogen produced in a chemical reaction.
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What was the hypothesis? (discovery of noble gases)
The nitrogen produced from air also contains other unknown gases.
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What was the experiment? (discovery of noble gases)
Fractional distillation of air separated the noble gases from nitrogen.
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What is the pattern in the boiling point and density of elements in group 0?
The boiling point and density of elements increase going down group 0 of the periodic table.
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What is the fact about the boiling point and density of a halogen?
The boiling point and density of any noble gas will be midway between those of the gases above and below it in the group.
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Other cards in this set

Card 2

Front

When do covalent bonds form?

Back

Covalent bonds form between atoms of non-metal elements.

Card 3

Front

What are the properties of metallic substances? (5 points)

Back

Preview of the front of card 3

Card 4

Front

What makes metals malleable?

Back

Preview of the front of card 4

Card 5

Front

Why do metals have high melting and boiling points?

Back

Preview of the front of card 5
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Comments

crimson_09

Where are the alkali metals found is the periodic table?

   In group 1.

Where are the alkali metals found *In the periodic table?

In group 1.

Other than that brilliant notes thank you .

andrewmf15

 I've just fixed the error :))

Thanks

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