C3.1 Periodic Table

Question 1

What did Newland suggest about the periodic table?

Answer 1

• He noticed after arranging the atoms in order of atomic mass that every 8th element had similar properties - “Law of Octaves”
• Suggested arranging them in octaves (called Newman’s Octaves)

Question 2

Why were atoms arranged in atomic mass in the early 1800s?

Answer 2

There was no such thing as atomic number as atomic structure (e.g protons and electrons) were unknown.

Question 3

What were the problems with Newland’s idea (3 points)?

Answer 3

• Some of his groups contained elements with no similar properties
• It left no gaps for undiscovered elements
• He mixed up metals and non-metals

Question 4

What did Mendleev suggest about the periodic table?

Answer 4

• Created “the table of elements”
• Put them in order of atomic mass (like Newland)
• Found he had to leave gaps to keep elements with same properties in the same groups (vertical columns)
• Gaps predicted properties of undiscovered elements at the time.

Question 5

When did scientists finally accept the periodic table?

Answer 5

When Mendleev’s predictions from the gaps he left were proven true by newly discovered elements

Question 6

How did scientists attitude towards the periodic table change over time (three steps)?

Answer 6

Scientists regarded the periodic table:

• First as a curiosity : when there was no evidence for it
• Then as a useful tool : when Mendleev was proven right) - And finally as an important summary of the structure of atoms : when atomic structure was discovered and it fit with the periodic table

Question 7

How are elements in the modern day periodic table arranged?

Answer 7

By order of atomic number (after the discovery of atomic structure)

Question 8

How are groups arranged?

Answer 8

Into columns by the number of electrons in the outer shell

Question 9

What does the group number tell you?

Answer 9

The amount of electrons in the outer shell

Question 10

How are periods arranged?

Answer 10

Into rows by the number of shells of electrons

Question 11

What is Group 1 of the periodic table known as?

Answer 11

The alkali metals

Question 12

What are the trends as you go down the alkali metals group (2) ?

Answer 12

The lower down, the higher the reactivity and the lower the melting/boiling points

Question 13

What are the first three metals of the group 1?

Answer 13

Lithium, Sodium, Potassium

Question 14

What are the properties of the alkali metals (2) ?

Answer 14

• Low density (first three less dense than water)

- Very reactive (only one outer electron)

Question 15

Why is alkali metals more reactive the further you go down the group?

Answer 15

• The further you go down, the more shells between the nucleus and the outer shell with one electron, as well as there being more distance between it and the nucleus
• The other electrons in the shell shield the nucleus’s positive attraction to the electron and repel the electron with negative charge.
• This means it is easier to lose the electron, making it more reactive.

Question 16

How do alkali metals react with water?

Answer 16

• Vigorously, they fizz and float around on the surface.
• Produce hydrogen
• Form hydroxides which dissolve in water to form alkali solutions.

Question 17

How do alkali metals react with non-metals?

Answer 17

• They form ionic bonds.

- White compounds are formed which dissolve in water to make colourless solutions.

Question 18

What is group 7 of elements known as?

Answer 18

The Halogens

Question 19

What are the trends as you go down the halogens group (2) ?

Answer 19

• The more you go down, the less reactive.

- The more you down, the higher the melting/boiling point.

Question 20

Why is halogens less reactive the further you go down the group?

Answer 20

• The further you go down, the more shells between the nucleus and the outer shell as well as there being more distance between it and the nucleus
• The other electrons in the shell shield the nucleus’s positive attraction to the shell and repel it with negative charge.
• This means it is harder to gain another electron as there is less attraction.

Question 21

What are the first four elements of the halogen group?

Answer 21

Flourine, chloride, bromine, iodine

Question 22

What are the properties of fluorine?

Answer 22

Very reactive, poisonous yellow gas

Question 23

What are the properties of chlorine?

Answer 23

Fairly reactive, poisonous dense green gas

Question 24

What are the properties of bromine?

Answer 24

Dense, poisonous, red-brown volatile liquid

Question 25

What are the properties of iodine?

Answer 25

Dark grey, crystalline solid, purple vapour

Question 26

How do halogens react with metals?

Answer 26

They form negative ions - halides

Question 27

Describe displacement in the halogen group.

Answer 27

More reactive halogens can replace less reactive ones in their salt solutions e.g chlorine can replace bromine in bromide.

Question 28

List the properties of the transitional metals in comparison to alkali metals.

Answer 28

• Much denser, shinier, harder and stronger.
• Much higher melting points (except mercury)
• Much less reactive - not as vigorous with water & oxygen

Question 29

What property do transitional metal ions have?

Answer 29

Each metal has more than one with different charges

Question 30

What property do transitional metal compounds have?

Answer 30

They all have different colours

Question 31

What are transitional metals and their compounds useful for?

Answer 31

They make good catalysts

Question 32

Why are alkali metals known as that?

Answer 32

They have a PH more than 7 when reacted with water