They have no chrge overall, which means they have the same number of protons as electrons.
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What is an element?
A substance made up of atoms that all have the same number of protons in their nucleus
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What is an example of an atom with 1 proton in it's nuclues?
Hydrogen
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Name the atom represented by this symbol: C
Carbon
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What is this symbol: Fe
Iron
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What do mixtures contain at least 2 of?
Elements and compounds.
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Name a mixture and their elements
Air - gases, (mainly nitrogen, oxygen, co2, and argon)
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Name 2 methods a mixture can be seperated by
Crystalisation & Chromotagraphy
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What is chromoagrphy used for?
To seperate different dyes in an ink.
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How are the dyes seperated in chromotagrphy?
The dyes in the ink on the chromotagraphy paper moves up at different speeds.
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What is distilisation used for?
To seperate mixtures which contain liquids.
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What do electrons move in?
Shells.
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How many electrons are allowed in each shell?
1st shell - 2, 2nd shell - 8, 3rd shell - 8
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When are atoms more stable?
When they have full electron shells.
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What happens when the outer shell is not full?
The atoms will react to fll it.
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How did scientists arrange the elements into the periodic table bck in the 1800's?
They used the relative atomic mass
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Why were there gaps in the first periodic table?
Because not all atoms had been found yet.
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Why was it wrong to put the elements in order of atomic mass?
It meant that some elements were also put into the wrong group/coloum.
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How is the modern periodic table that we have today, laid out?
In order of increasing atomic number
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Where are metals and non metals found?
Metals are on the left of the periodc table and non metals are found on the right.
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Why are elements arranged in groups and what does this mean?
Because they all have simelar properties which means they all react in simelar ways.
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In group 1, the metals react more violently as you go down the group true or false?
True.
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What are group 7 elements know as?
Th halogens.
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Name 2 of the halogen elements.
Iodine & bromine.
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What do halogens contain?
2 atoms.
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What do you notice as you go down group 7?
The halogens become less reactive, which eans its harder to gain an electron as the outer shell is further from nucleus, have higher melting/boiling points and have higher relative atomic mass.
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Why do group 7 elements react in simelar ways?
Because they all have 7 electrons in their outer shell.
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What can halogens form and how?
Moleular compound by reacting with non metals which shares electrons and form covalent bonds so they get a full outer shell.
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