P4 - Atomic and Mass Numbers

What does the atomic number tell you?

The number of protons in the nucleus of an atom

What does the mass number tell you?

The total number of protons and neutrons in the nucleus

How do you calculate the number of neutrons in an atom?

Mass number - Atomic number

How do you calculate the number of electrons in a neutral atom?

Same as the number of protons

What is the charge of a proton?

+1 (positive)

What is the charge of a neutron?

0 (no charge, neutral)

What is the charge of an electron?

-1 (negative)

Why do atoms have no overall charge?

Because the number of protons equals the number of electrons

Where are protons and neutrons found in an atom?

In the nucleus

Where are electrons found in an atom?

In energy levels (shells) around the nucleus

What is an isotope?

Atoms of the same element with the same number of protons but different numbers of neutrons

What stays the same in isotopes of an element?

The atomic number (number of protons)

What changes in isotopes of an element?

The number of neutrons (and therefore the mass number)

Are all isotopes radioactive?

No, but many isotopes are radioactive

What is an ion?

An atom that has gained or lost electrons and therefore has a charge

What happens when an atom loses one electron?

It becomes a positively charged ion with a charge of +1

What happens when an atom loses two electrons?

It becomes a positively charged ion with a charge of +2

What is the charge on an ion if a sodium atom (11 protons) loses one electron?

1

What subatomic particle determines the element?

The number of protons

What must be true for an atom to be sodium?

It must have 11 protons

Can you tell the number of neutrons from the atomic number alone?

No, you need the mass number too

Why is a sodium ion positively charged after losing an electron?

Because it has more protons (+11) than electrons (-10)