Periodic table
An arrangement of elements in periods and groups in order of increasing proton/atomic number
Periodic trends: metallic character
Decreases as you move across period (left to right)
Periodic trends: group number
Corresponds number of outermost electrons + tells us charge -> group 1 elements from 1+ ions and Group 7 elements from 1-
Periodic trends: elements in the same group
Similar chemical properties -> due to having the same number of electrons in their outer shell (chemical peoperties depend on outermost electrons)
Physical properties of alakli metals (group 1)
- Silvery coloured metals
- Soft -> easily cut with a knife
- Low melting and boiling point
- Low densisties
Chemical properties of alkali metals (group 1)
- highly reactive metals
- oxidises easily
- reactivity increases on descending the group
Observations of reaction with water (group 1 metals) -> lithium
- when cut it reveals a shiny surface
- fizzing, floating
- when adding universal indicator it turns blue/purple
- positive test for hydrogen
Observations of reaction with water (group 1 metals) -> sodium
- floating around surface, fizzing
- turns into a perfect sphere as its melting
- when adding universal indicator, turns blue/purple
- positive test for hydrogen
Observations of reaction with water (group 1 metals) -> potassium
- lilac flame
- floating, moving faster
- fizzing
- forms sphere
Equation of reaction of group 1 metal with water
Metal + water -> metal hydroxide + hydrogen
KEY PROPERTIES metal group 1 -> melting point
- as you go down group 1, the melting point decreases due to weaker forces of attraction (between metal atoms)
KEY PROPERTIES metal group 1 -> denisty
- As you go down group 1, denisty increases
KEY PROPERTIES metal group 1 -> reactivity
As you go down group 1 reactivity increases because:
- greater distance between nucleus and outer shell electron
- attraction becomes weaker (nuclear attraction)
- greater shielding effect
- atoms get larger
SO: EASIER TO LOSE OUTER SHELL ELECTRON
Halogens (group 7)
- Increasing denisty
- non-metals so don’t conduct electricty
- exist as diatomic molecules
- decreasing reactivity
Physical state of halogens changes as you go down the group -> chlorine
Pale yellow-green gas
Physical state of halogens changes as you go down the group -> flourine
Yellow gas
Physical state of halogens changes as you go down the group -> bromine
Red/brown liquid
Physical state of halogens changes as you go down the group -> iodine
Grey/black solod
Group 7 elements get LESS reactive as you go down the group because?
- larger atoms
- weaker attraction between nucleus and outer shell (nuclear attraction)
- greater shielding effect
- HARDER to gain electron
Properties of transition metals
- high densities -> higher than grouo 1 alkali metals
- high melting points -> higher than group 1 alkali metals
- stronger than group 1 alkali metals
- form coloured compounds
- often act as catalysts as elements in compounds
- hard, strong and brittle
Noble gasses (group 0 elements)
- unreactive and don’t easily form molecules -> have a full outer shell
- stable arrangements of electrons
- all of them have 8e- in outer shell, except helium which has 2
Uses of noble gasses
- neon lights
- manufactiring of halogen headlights
