Elements are arranged on the periodic table in order of , where each element has one proton than the element preceding it.

The table is arranged in vertical columns called numbered 1 – 8 and in rows called .

Period:these are the horizontal rows that show the number of shells of electrons an atom has. E.g: elements in Period 2 have two electron shells, elements in Period 3 have three electron shells.

Group:these are the vertical columns that show how many outer electrons each atom has. E.g: Group 4 elements have atoms with 4 electrons in the outermost shell, Group 6 elements have atoms with 6 electrons in the outermost shell.

Because there are in the way the elements are arranged on the Periodic table, there are also and in the chemical behaviour of the elements.

There are trends in properties down Groups and across a Period. All of the Group I elements, for example, react very quickly with water. In this way the Periodic table can be used to how a particular element will behave.

Elements on the left, in Group 1, are all metallic.

Elements in Group 2 are also metallic, but their metallic properties are less apparent than the elements in Group 1.E.g. They are less reactive.

As you go across the group, elements slowly become less metallic, and elements in Group 4 become non-metals. However, they are still generally in the solid form.

As you progress group 6,7,8 elements tend to be in the gaseous form.

● Group number- shows the number of electrons in the outer shell

● Metallic /nonmetallic- metals form positive ions by losing electrons and nonmetals form negative ions by gaining electrons. All of group 1 and 2 are metals, all of group 7 and 8 (0) are nonmetals. In groups 3,4,5,6 there is a transition between metals and nonmetals.

The Group I metals are also called the alkali metals as they form with high pH values when reacted with water.

Group 1 metals are lithium, sodium, potassium, rubidium, caesium and francium.

They all contain just in their outer shell.

- Are soft and easy to cut, getting and as you move down the Group (sodium and potassium do not follow the trend in density).

- Have silvery surfaces when freshly cut.

- Conduct heat and electricity.

- They all have melting points and densities and the melting point as you move down the Group.

- They react readily with oxygen and water vapour in air so they are usually kept under to stop them from reacting.

- Group 1 metals will react similarly with water, reacting vigorously to produce an metal hydroxide solution and gas.

Halogens -> State at Room Temperature -> Colour -> Reaction with Halide ions

Chlorine -> Gas -> Yellow-Green -> Oxides bromine and below

Bromine -> Liquid -> Red-Brown -> Oxides iodine and below

Iodine -> Solid -> Purple -> Oxides a state and below

● Melting point

o Low melting points compared to most other metals

▪ As you go down the group, melting points decrease

● Density

o Low densities - they will float on water

▪ As you go down the group, densities increase

● Reaction with water

o All react vigorously with water to create an alkaline solution and hydrogen (i.e. you will see bubbling/effervescing due to the production of a gas)

▪ Reactivity increases down the group (so reaction becomes more vigorous)

▪ It is easier to lose electrons due to the increase in electron shells and therefore there is more electron shielding and easier to lose electrons due to the decrease in attraction between the positively charged nucleus and the negatively charged outer shell electrons

The group VII elements are called halogens. They are poisonous non-metals that have low melting and boiling points that increase down the group. As a result of this increasing boiling and melting points, the state of the halogens at room temperature, changes from gas to liquid to solid down the group (fluorine and chlorine, the first and second halogens, are a gas; bromine, the third halogen is a liquid; and iodine, the fourth halogen, is a solid). The colours of halogens also get darker down the group.

Metal + Halogen ———–> metal salt (halide)

Example: Sodium + Chlorine ———-> Sodium chloride

The salts that halogens form when they react with metals are called halides (chloride, bromide, iodide for example)

When a halogen reacts with a halide, the more reactive halogen will 'displace' (more about displacement reactions ) the less reactive halogen.

Example:

chlorine + potassium bromide ———–> potassium chloride + bromine

(here, chlorine is more reactive than bromine so chlorine will replace the bromine in potassium bromide to form potassium chloride)

So, fluorine will displace all the other halides, since it is the most reactive of them. Chlorine will displace all halides except fluoride. Bromine will displace all halides except fluoride and chloride, and so on.

Now you can predict how the halogens will be up and down the group. Astatine, the fifth halogen, will have high melting and boiling points so will be solid at room temperature, and will have a very dark colour.

Similar​ ​chemical​ ​properties​ ​due​ ​to​ ​the​ ​fact​ ​that​ ​they​ ​have​ ​the​ ​same​ ​number​ ​of outer​ ​shell​ ​electrons

Once​ ​you​ ​are​ ​given​ ​information​ ​regarding​ ​more​ ​than​ ​one​ ​element​ ​in​ ​a​ ​group, look​ ​at​ ​each​ ​of​ ​their​ ​positions​ ​in​ ​the​ ​group​ ​(i.e.​ ​near​ ​the​ ​top​ ​or​ ​bottom)​ ​and identify​ ​the​ ​trend​ ​shown​ ​by​ ​the​ ​elements​ ​with​ ​given​ ​information​ ​(e.g.​ ​reactivity or​ ​boiling​ ​point​ ​could​ ​increase​ ​down​ ​the​ ​group)

Going​ ​down​ ​a​ ​group​ ​means​ ​going​ ​up​ ​in​ ​number​ ​of​ ​electron​ ​shells,​ ​more electron​ ​shielding​ ​and​ ​so​ ​less​ ​attraction​ ​between​ ​the​ ​nucleus​ ​and​ ​outer shell​ ​electrons

- They are very and strong metals and are good conductors of and

- They have very points and are highly metals. E.g: the melting point of titanium is 1,688ºC whereas potassium melts at only 63.5ºC

- The transition metals form compounds and often have more than one oxidation state.

- Transition metals are often used as

Noble gases are unreactive because their outer shell are full. This means that they are stable without having to gain or lose electrons. They are also described as inert.

Under normal conditions, noble gases are odourless, colourless and nonflammable.

Argon is used in lightbulbs.

Helium is used to inflate tires and balloons

Neon is used in neon lights because it glows when electricity is passed through it.

Xenon is used in photocopying.