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Colour
The halogens become darker as you go down the group. Fluorine is very pale yellow, chlorine is yellow-green, and bromine is red-brown. Iodine crystals are shiny purple - but easily turn into a dark purple vapour when they are warmed up.

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What they are
The halogens are a group in the periodic table consisting of five elements with the same properties: fluorine, chlorine, bromine, iodine, and astatine.

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properties of alkaline earth metals are:
shiny
silvery-white
low densities
low melting points
low boiling points
somewhat reactive at standard temperature and pressure
and very reactive.

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Halogens are bleaching agents. They will remove the colour of dyes. Chlorine is used to bleach wood pulp to make white paper.

Halogens kill bacteria. Chlorine is added to drinking water at very low concentrations. This kills any harmful bacteria in the water, making it safe to drink. Chlorine is also added to the water in swimming pools.

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Salal- Properties of Alkaline Earth Metals

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Salal- Properties of Alkaline Earth Metals

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Alkaline Earth Metal have properties which include;

High Boiling and Melting Points
Low Density
Ductile
Malleable
Usually Silver
Have two electrons in outer Shell
React Easily with Water

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Group 0 contains solely non-metal elements and are placed on the far right of the periodic table, called the noble gases. All the elements exist as single atoms. They show trends in their physical properties. They are inert, or unreactive, because they have a complete shell of valence electrons, therefore they do not have the tendency to lose, gain or share electrons in ionic or covalent bonding. Their main properties include low densities and being inert and not flammable

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The alkali metals physical properties:

are soft (they can be cut with a knife)

have relatively low

melting points

The alkali metals also have low densities. They are low enough for the first three (lithium, sodium and potassium) to float on water.

Reactions with water

The alkali metals react with water to produce a metal hydroxide and hydrogen. For example, sodium reacts with water:

Sodium + water → sodium hydroxide + hydrogen

2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g)

Sodium hydroxide is an alkali. It is a base that dissolves in water to form an alkaline solution. This solution:

has a

pH

greater than 7

turns

universal indicator

solution blue or purple

Hydrogen gas is also produced. With very reactive metals such as potassium, the energy of the reaction causes the hydrogen to burn as the reaction takes place.

Rubidium is placed below potassium in group 1. Predict what is seen when rubidium is added to water.

Rubidium should melt very quickly. It should burn very violently, and disappear almost instantly with an explosion.

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There are 6 types of Noble gases. The six noble gases that occur naturally are helium (He), neon (Ne), argon (Ar),krypton (Kr), xenon (Xe), and the radioactive radon (Rn) They are present in the Earths atmosphere and can be obtained by fractional distillation. They make up a group of chemical elements with similar properties like colorless and odorless. They have a very low chemical reactivity.

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Introduction
They are the elements in the middle section of the periodic table. They occupy the middle portions of the long periods of the periodic table of elements between the groups on the left-hand side and the groups on the right. Specifically, they form Groups 3 (IIIb) through 12 (IIb).

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The Alkali metals are extremely reactive metals, located in group one on the periodic table, that have only one electron in their outer shell. Alkali metals are good conductors of heat and electricity. Out of all of the alkali metals, the two most reactive elements are Cesium and Francium, which, like all other elements in this group, will explode when exposed to water

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Fluorine has an atomic number of 9
Chlorine has the atomic number 17
Bromine has an atomic number of 35
Iodine has the atomic number 53
Astatine has an atomic number of 85

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The noble gases are colourless, odourless, tasteless, nonflammable gases. They traditionally have been labeled Group 0 in the periodic table because for decades after their discovery it was believed that they could not bond to other atoms; that is, that their atoms could not combine with those of other elements to form chemical compounds. Their electronic structures and the finding that some of them do indeed form compounds has led to the more appropriate designation, Group 18.

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Transition metals have typical properties of metals as they are malleable and can conduct  electricity and heat. They have high melting points. Transition metals also form cations when they react with non-metals (due to them losing electrons rather than gaining).

However, some elements do not represent all of the properties. For instance, mercury melts at -39°C and is a liquid at room temperature.

Iron is used as a catalyst to form ammonia in the Haber process. Iron oxide is useful as it makes hydrogen by reacting carbon monoxide and steam together.

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The boiling points of the noble gases are very low. Helium at the top of the group as the lowest boiling point, at approximately 270 degrees Celsius. The boiling point increases going down the group, because going down the group means that the atoms become larger, the inter-molecular forces between the atoms become stronger, and therefore more energy is required to overcome these forces.

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Uses
Many of elements in the transition elements are technologically important. For example, titanium,  iron, nickel, and copper , are used structurally and in electrical technology. Second, the transition elements form many useful alloys, with one another and with other metallic elements. Third, most of these elements dissolve in mineral acids, although a few, such as platinum, silver, and gold, are called “noble”—that is, are unaffected by simple (nonoxidizing) acids.

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properties of transition metals:

Good conductors of heat and electricity.

Can be hammered or bent into shape easily.

They are less reactive than alkali metals

They have high melting points

transition metals have color

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Noble gases are all odorless and colorless with a very low chemical reactivity. The six noble gases are helium, neon, argon, krypton, xenon and Radon. Because of their low reactivity they are not able to combine with other elements to form compounds
,

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The transition elements may be subdivided according to the electronic structures of their atoms into three main transition series, called the first, second, and third transition series ('d'-block), and two inner transition series, called the lanthanoids and the actinoids ('f'-block).

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Why are they called transition metals?

The elements in groups 1B through 8B (also known as 3 through 12) are called the transition metals. Sometimes this block of elements are referred to as the d block. They are called d block elements because the electrons being added in this block of elements are being added to the d orbitals.

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The noble gases have various uses linked to their properties.
Helium is used as a lifting gas in airships and smaller party balloons, because it is less dense than air , causing these items to rise, and it is non-flammable, therefore it cannot be set on fire.
Argon is used as a protective gas in welding pieces of metal together, because they are denser than air and so stop air from reaching the metal, and they are inert so the hot metal cannot oxidize & spoil the weld.