The periodic table

Question 1

Easy52%

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.

[1]

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

[1]

The table below shows the boiling points of four elements in Group 7 (the halogens).

Element	Boiling point ( $∘C^\circ\text{C}$ )
Fluorine	$- 188$
Chlorine	$- 34$
Bromine	$X$
Iodine	$184$

Predict the value of $X$ .

[1]

When chlorine gas is bubbled through a solution of potassium bromide, a displacement reaction occurs. State the color change observed in the solution.

[1]

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

$F\text{F}$
$F2\text{F}_2$
$F2\text{F}^2$
$2F2\text{F}$

[1]

The periodic table

Question 1

The periodic table Questions

The periodic table

Question 1

The periodic table Questions