Atoms and elements

What are the subatomic particles in an atom?

Neutrons protons and electrons

Explain where and what the nucleus is.

• In the middle of the atom

• Contains neutrons and protons

• the radius is about 1 ×10^-14

• It has a positive charge because of the protons

• Almost the whole mass of the atom is concentrated at the nucleus

Explain where and what electrons are?

• Move around the nucleus in shells

• Negatively charged

• The volume of their orbits determine the size of the atom

• Electrons has virtually no mass

What are the masses and charges of subatomic particles?

Do atoms have a charge?

No they are neutral because they have the same number of protons and electrons

Why do ions have charges?

The proton and electron numbers aren’t equal so the charges do not cancel out

What does the atomic number tell you?

How many protons there are

What does the mass number tell you?

the total number of protons and neutrons in an atom

Where are the atomic number and atomic mass on a nuclear symbol?

What is the definition of an element?

a substance made up of atoms that all have the same number of protons

What is the role of protons in an element?

Decides what type of atom it is

What is the definition of an isotope?

different forms of the same element, which have the same number of protons but different numbers of neutrons

What is relative atomic mass?

average mass taking into account the different masses and abundances of all the isotopes that make up that element.

What is the formula for relative atomic mass?

A_r = sum of (isotope abundance x isotope mass number) / sum of abundances of all the isotopes