Chemistry A Atomic Structure And Periodic Table Flashcards
What is a element
A substance that is made up of only one type of atom
What is a compound
A substance made up of two or more different elements bonded together
How is a atom structured
“In the centre there is a nucleus made up of protons and neutrons. Electrons orbit the nucleus in shells
Atomic mass = neutron + protons
Atomic number = protons”
How are electrons arranged
“Electrons will fill the shell closest to the nucleus first. Each shell can hold a specific number of electrons.
1st shell = 2
2nd shell = 8
3rd shell = 8”
Properties of Group 1
elements
• Soft
• Low melting point
• Low density
• Metals
• Conduct electricity
Group 1 elements react with water
When group 1 metals react with water:
• pH of the solution increases (becomes alkaline)
• Fizzing/bubbling (Hydrogen gas is produced)
• The metal floats on water (metal is less dense than water)
• The metal becomes a molten sphere
• Potassium produces a lilac flame
Trend in reactivity down
Group 1
The Group 1 metals get more reactive down the group. This is due to the outer electron being further away from the nucleus therefore weaker electrostatic attraction, so the electron is more easily lost
The appearance of Group 7 elements
Fluorine: Colourless gas
Chlorine: Pale-yellow gas
Bromine: Orange liquid
lodine: Grey solid with a purple vapor
The trend in physical properties as you go down group 7
As you go down the group:
-colours get darker
-boiling point increases
Trend in reactivity down group 7
Halogens get less reactive down the group. This is due to the outer electron shell being further away from the nucleus therefore weaker electrostatic attraction electron is less easily gained
Displacement reaction
When a more reactive halogen takes place of a less reactive halogen in a compound (from its salt).
Chlorine + sodium bromide - sodium chloride + bromine
Properties of the group 0 elements
Group 0 elements are called the Nobel gases. They are unreactive because they have a full outer shell of electrons. They do not need to lose or gain any electrons
Properties of transition metals
- hard
- conduct electricity and heat
- hught melting points
- malleable
Trends on the periodic table
The group number indicates how many electrons are in the outer shell of an atom:
As you go down a group, the number of electron shells increases by 1
As you go across the Periodic Table, the number of electrons in the outer shell increases by 1
