The periodic table we use today is based on the work of Dmitri Mendeleev.

Mendeleev left gaps in his early periodic table. State one reason why he left these gaps.

Mendeleev ordered elements mainly by atomic weight, but he switched the positions of some elements, such as cobalt and nickel. Explain why he did this.

The table below shows the melting points of four elements in Group 1 (the alkali metals).

Element	Melting point ( $∘C^\circ\text{C}$ )
Lithium	$181$
Sodium	$98$
Potassium	$Y$
Rubidium	$39$

Predict the value of $Y$ .

When bromine water is added to a solution of potassium iodide, a displacement reaction occurs. State the color change observed in the solution.

Which of the following is the correct chemical formula of a bromine molecule?

$Br\text{Br}$
$Br2\text{Br}_2$
$Br2\text{Br}^2$
$2Br2\text{Br}$

The periodic table we use today is based on the work of Dmitri Mendeleev.

Mendeleev left gaps in his early periodic table. State one reason why he left these gaps.

Mendeleev ordered elements mainly by atomic weight, but he switched the positions of some elements, such as cobalt and nickel. Explain why he did this.

The table below shows the melting points of four elements in Group 1 (the alkali metals).

Element	Melting point ( $∘C^\circ\text{C}$ )
Lithium	$181$
Sodium	$98$
Potassium	$Y$
Rubidium	$39$

Predict the value of $Y$ .

When bromine water is added to a solution of potassium iodide, a displacement reaction occurs. State the color change observed in the solution.

Which of the following is the correct chemical formula of a bromine molecule?

$Br\text{Br}$
$Br2\text{Br}_2$
$Br2\text{Br}^2$
$2Br2\text{Br}$

1.2 The periodic table

Question 6

Markscheme

1.2 The periodic table

Question 6

Markscheme

1.2 The periodic table

Question 6

1.2 The periodic table Questions

1.2 The periodic table

Question 6

1.2 The periodic table Questions