Four statements about atoms are listed.
1 The centre of an atom is positively charged.
2 Protons and electrons are located in the nucleus.
3 Protons and electrons have the same mass.
4 Most of the mass of an atom is in the nucleus.
Which statements are correct?
1 and 2
1 and 4
2 and 3
3 and 4
Atoms and ions are made from small particles called electrons, neutrons and protons.
Complete the table.
The structure of an atom of element X is shown.
key
- = electron
n= neutron
p= proton
What is element X ?
boron
carbon
sodium
sulfur
4 X and Y are two different elements.
X and Y have the same number of nucleons.
Which statement about X and Y is correct?
They have the same physical properties.
Their atoms have the same number of electrons.
They are in different groups of the Periodic Table.
They have different relative masses.
What is the total number of electrons in one molecule of ammonia, ?
6
8
10
11
The electronic configurations of two elements are given.
element L: 2,8,8,1
element M: 2,8,4
Which row identifies the group number and the period number for element L and element M ?
group number
period number
group number
period number
I
4
IV
3
I
4
III
4
IV
1
III
4
IV
1
IV
3