Chemistry GCSE AQA Year 9: Atomic structure and the periodic table

What is group 1 called?

Alkali metals

What is the balanced symbol equation for sodium reacting with water and is the product acid or alkaline? Why?

2Na + 2H2O -> 2NaOH (the hydroxide ion (OH-) is alkaline) + H2

What are the properties of alkali metals?

. Very soft

. Malleable

. Conduct electricity

. Low density - float on water

. Briefly shiny, quickly become dull when they react with air

What is the balanced symbol equation for sodium reacting with oxygen?

4Na + O2 -> 2Na2O

How do alkali metals react?

by losing one electron from outermost shell

What happens to reactivity going down group 1 and why?

. As you go down, number of shells increases

. So distance between nucleus and outer shell increases

. So shielding (electrons in inner shells reduce attraction between nucleus and outer electron) increases

. So the electron is lost more easily

. So reactivity increases going down group 1

What is shielding?

Electrons in inner shells reduce attraction between nucleus and outer electron

What are some observations when alkali metals react with water?

. Bubbling

. Movement

. Metal getting smaller

. The more reactive the metal, the greater the effect - K burned with a lilac flame

What is group 7 called?

Halogens

How do you know if an atom is diatomic?

If it ends in 'ine' or 'gen'

What bond do the diatomic elements have with each other?

Covalent bond - share a pair of electrons

Describe chlorine at room temperature

Pale green gas

Describe bromine at room temperature

Brown liquid

Describe iodine at room temperature

Grey/purple solid

How do halogens react?

By gaining 1 electron

What happens to reactivity going down group 7 and why?

. As you go down the group, number of shells increases

. So distance between nucleus and outer shell increases

. So shielding (electrons in inner shells reduce attraction between nucleus and outer electron) increases

. So the electron is gained less easily

. So reactivity decreases going down group 7

What are elements ordered by in the current periodic table?

Atomic number

Who is credited with the first 'periodic table'?

Mendeleev

What did elements used to be ordered by?

Atomic mass

How did Mendeleev organize his periodic table?

. Did not follow atomic mass

. Instead tried to match elements according to properties

. Left gaps where he thought elements were missing

What is group 8 called?

Noble gases

What are some properties of noble gases?

. Colourless

. odourless

. Have full outer shells so very unreactive

. Last group to be discovered