Atomic structure and the periodic table - questions 61-75

Explain the pattern in reactivity as you go down group 7.

Decreases because the atoms get larger going down the group. This means that the outer shell gets further away from the nucleus and is shielded by more electron shells. The further the outer shell is from the positive attraction of the nucleus, the harder it is to attract another electron to complete the outer shell.

Why do halogens often pair up together to form diatomic molecules?

Halogens have 7 electrons on their outer shell, they need one more electron to have a full outer shell. Because of this, each atom pairs with another atom and shares an electron (covalent bond), forming a diatomic molecule.

What happens when halogens react with a different element?

They gain an electron into their outer shell and become negative ions. When this happens, they are called halides.

Name the physical properties of halogens.

Non metals and do not conduct electricity. They are brittle and crumbly as solids. They are poisonous and smelly. As you move down the group, they become darker in colour.

At room temperature, what colour and state are fluorine, chlorine, bromine and iodine?

Fluorine is a yellow gas. Chlorine is a green gas. Bromine is a red-brown liquid. Iodine is a grey solid.

In solution, what colour is chlorine, bromine and iodine?

Chlorine is pale green, bromine is orange, iodine is dark brown.

What would happen in this reaction : fluorine + sodium chloride → sodium fluoride + chlorine?

Fluorine is the more reactive halogen, so will displace chlorine from the sodium chloride compound. The yellow colour of chlorine would be seen as it is a product.

Where are transition metals found in the periodic table?

In the middle section.

Describe the properties of transition metals.

Good conductors of heat and electricity, dense, shiny and strong.

Compare the reactivity of transition metals with group 1 elements.

Transition metals are less reactive than group 1 and do not react as vigorously with water, oxygen or group 7 elements.

Compare the density and hardness of transition metals with group 1 elements.

Transition metals are denser, stronger and harder than group 1 metals.

Compare the melting point of transition metals with group 1 elements.

Transition metals have higher melting points.

What ions do transition metals form?

Most transition metals can form ions with different charged ions.

What do transition metal compounds normally look like?

They form different coloured compounds.

Give a use of transition metals in industry.

Transition metals and their compounds make good catalysts.