Core

Question 1

What does the group number of an element tell you?

Answer 1

The group number shows how many electrons the element has in its outer shell.

Question 2

What does the period number of an element tell you?

Answer 2

The period number shows how many electron shells the element has.

Question 3

What is an element?

Answer 3

An element is a substance made from atoms with the same number of protons in the nucleus.

Question 4

What is an atom?

Answer 4

An atom is the smallest particle of an element that still has its chemical properties.

Question 5

What is a molecule?

Answer 5

A molecule consists of two or more atoms chemically joined together.

Question 6

What is a compound?

Answer 6

A compound consists of two or more elements chemically joined together.

Question 7

What is an ion?

Answer 7

An ion is a charged particle formed when an atom, or group of atoms, loses or gains electrons.

Question 8

How was Mendeleev’s periodic table arranged?

Answer 8

1) Mendeleev put the elements in order of the relative atomic masses.
2) He checked the properties of the elements and their compounds.
3) He swapped the places of some elements so that elements with similar properties lined up.
4) He left gaps where he thought there were other elements and predicted their properties.
5) When these elements were discovered, Mendeleev’s predictions fitted the properties very well.