Atoms have a positively-charged nucleus made of protons and neutrons, and negatively-charged electrons that orbit the nucleus in shells.
What is the relative mass of an electron?
The number of protons (p), electrons (e) and neutrons (n) in an atom of 23Na is:
11p, 11e and 11n
11p, 11e and 12n
12p, 12e and 11n
The number of electrons in the nitride ion N3- is:
The electronic configuration for a calcium atom 40Ca is:
The relative charge on a neutron is:
Which of the following statements is true about two isotopes of an element?
They have the same atomic number and mass number.
They have the same mass number but different atomic numbers.
They have the same atomic number but different mass numbers.
What is the relative atomic mass of chlorine if there is 75% of 35Cl and 25% of 37Cl?
Which of the following statements is true about a compound?
It contains atoms of different elements chemically joined together.
It contains atoms of different elements mixed together.
It contains atoms of the same element chemically joined together
The number of electrons in a potassium ion K+ is: