The Periodic Table And The First 20 Elements (T2)

Question 0

Across each period, from left to right, what happens?

Answer 0

Across each period from left to right, an energy level gradually fills with electrons.

Question 1

When you move up and down the different period levels (the left hand side) what is the constant in each element?

Answer 1

As you move up and down the different periods rows, the number is energy levels is the same as the period number.

Question 2

Moving along each group, what happens?

Answer 2

Moving along each group, the number of electrons in the highest occupied energy level is the same as the group number.

Question 3

Each element in a group has the same number of electrons in its outer shell? What is the exception to this rule?

Answer 3

Group 0 is the exception as it contains helium (He) with only two electrons in the outer shell.

Question 4

How do you draw an elements electronic structure from the information on the periodic table?

Answer 4

1) find the element, work out its period number and draw that many circles around the nucleus
2) work out the group number and draw that many electrons in the outer circle
3) fill the other circles in with electrons
4) count the electrons and make sure they equal the atomic number

Question 5

Group one is…

Answer 5

Alkali metals (except hydrogen which is a gas)

Question 6

Group two is..

Answer 6

Alkaline earth metals

Question 7

Group 0 is..

Answer 7

Noble gases

Question 8

Describe the noble gases..

Answer 8

• all have a complete outer shell
• very up reactive due to the completed outer shells
• generally show inert behaviour and remain as a pure element in most cases
• have no colour, odour and are often used in refrigeration and lights
• all non metallic elements with very low melting and boiling points
• they form 1% of air and most of this is Argon (Ar)
• exist as single atoms due to their electrical stability (ie: they are monatomic molecules)
• all noble gases EXCEPT radon are separated by the fractional distillation of liquified air

Question 9

What elements are the noble gases?

Answer 9

Helium (He)
Neon (Ne)
Argon (Ar)
Krypton (Kr)
Xenon (Xe)
Radon (Rn)

Question 10

Down the group 0, the melting point and boiling point of noble gases steadily increases. Why?

Answer 10

• each new period row represents an extra energy level, producing an increasingly larger atom
• this results in an increase in intermolecular forces and bonding
• because the strength of the intermolecular forces / bonding increases, so does the boiling point

Question 11

The density of the noble gases increases or decreases down the group?

Answer 11

Increases

Question 12

Describe group 1, the alkali metals..

Answer 12

• very reactive, due to the single electron in the outer shell
• due to their high reactivity, they are able to bind onto anything and can react with chemicals often considered non reactive
• down the group, each one gets more reactive that the last
• contact with just water will release a lot of heat energy and create an alkaline product
• they are kept under oil to prevent them from reacting with oxygen or moisture in the air
• as you go down the group, the atoms get larger
• very soft and easily cut with a knife, getting softer as you go down the group
• shiny and silvery when freshly cut but tarnish within seconds of exposure to air
• the melting and boiling points are very low for metals and get lower as you go down the group

Question 13

The further you go down group 1, the larger the atom, and the larger the atom in group 1, the easier it is to cause a reaction. Why?

Answer 13

This is partly due to the distance between the outermost electron and the nucleus and inner shell - the further the distance, the weaker the attraction from the nucleus.

Question 14

List the alkali metals..

Answer 14

Lithium - Li
Sodium - Na
Potassium - K
Rubidium - Rb
Caesium - Cs
Francium - Fr

Question 15

Which of the alkali metals is radioactive and what is special about one of its isotopes?

Answer 15

Francium (Fr) is radioactive and one of its isotopes is produced during the radioactive decay of Uranium-235

Question 16

Why must you be careful not to touch the alkali metals with your bare hands?

Answer 16

Because a bit of sweat could give a reaction producing lots of heat and a very corrosive metal hydroxide.

Question 17

What happens when the alkali metals react with water? Give the standard word equation for the reaction.

Answer 17

They all react with water to produce a metal hydroxide and hydrogen.

Metal + cold water -> metal hydroxide + hydrogen

Question 18

Describe the Alkali Earth Metals, group 2…

Answer 18

• have two electrons in the outer shell, making them very reactive but not as reactive as group 1
• if exposed to water there is generally a reaction, but not as violent as group 1
• as we move down the group there is an increase in reactivity

Question 19

What are the Alkali Earth Metals?

Answer 19

Beryllium - Be
Magnesium - Mg
Calcium - Ca
Strontium - Sr
Barium - Ba
Radium - Ra

Question 20

With regards to the group two, Alkali Earth Metals, what is the “activation energy”?

Answer 20

Most of the group 2 elements require energy to be put in before they react.

This is known as the “activation energy”.

The activation energy is usually supplied by raising the temperature of the element.

Question 21

Describe the Halogens - group 7…

Answer 21

• halo-gen means “salt former”
• highly reactive due to only having one spare place in their outer shell
• they generally not require a small amount of activation energy
• down the groups they grow darker as the atoms get heavier
• as the atoms get larger the chemicals at room temperature are heavier, so the states at the middle of the group are liquid and the heavier ones are solids
• quite toxic, especially to bacteria, so often used in sterilisation
• the boiling point increases down the table due to the weights of the elements increasing

Question 22

Unlike groups 1 and 2, the reactions of elements in group 7 (the halogens) gets less vigorous as they get heavier. Why?

Answer 22

Because halogens have to gain one electron to complete the outer shell, so if the nucleus is further away from the outer shell, there will be a weaker positive charge from the nucleus pulling the negatively charged electrons from the other atoms.

Question 23

What is the colour of fluorine and its state at room temperature?

Answer 23

Fluorine starts yellow and a gas at room temperature.

Question 24

What colour and state is bromine at room temperature?

Answer 24

Bromine is a liquid and brown at room temperature.

Question 25

What are the halogens, group 7?

Answer 25

Fluorine - F
Chlorine - Cl
Bromine - Br
Iodine - I
Astatine - At

Question 26

Halogens all exist as ?????? molecules..

Answer 26

Halogens all exist as diatomic molecules.

Eg:

F2
CL2
Br2

Question 27

Give two points about fluorine..

Answer 27

• pale yellow gas

- most reactive non metallic element known

Question 28

Give three points about chlorine

Answer 28

• dense pale green gas
• highly reactive and very toxic
• used in WW1

Question 29

Give two points about bromine..

Answer 29

• dark red liquid, vaporises to an orange-brown vapour

- toxic and still pretty reactive

Question 30

Give two points about iodine..

Answer 30

• dark grey crystalline solid that on heating sublimes to give a brilliant purple vapour
• getting less reactive

Question 31

What are the halide ions?

Answer 31

Halogens form singly charge anions

Eg: Cl-

They gain an electron to become stable, giving a surplus charge of -1

These ions are called the “halide ions”

Question 32

When halogens combine with other elements in simple ionic compounds, how does the name change?

Use fluorine, chlorine, bromine and iodine as examples..

Answer 32

The end of the halogen element changes from …ine to …IDE.

Eg:

Fluoride (F-)
Chloride (Cl-)
Bromide (Br-)
Iodide (I-)

The other elements at the start of the compound remains unchanged.

Eg:

Potassium fluoride
Hydrogen chloride
Calcium bromide