Atomic Structure and Isotopes Flashcards

Flashcards about Atomic Structure and Isotopes

What is the atomic number?

The number of protons in the nucleus of an atom.

What is the mass number?

The number of protons plus the number of neutrons in the nucleus of an atom.

What are isotopes?

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

What is average atomic mass?

The weighted average of the masses of all the isotopes of an element.

What is an atomic mass unit (amu)?

A unit used to measure atomic mass.

What is isotopic abundance?

The percentage of an isotope in a representative sample of an element.

How is average atomic mass calculated?

(% Abundance Isotope 1) (Mass of Isotope 1) + (% Abundance Isotope 2) (Mass of Isotope 2) + (% Abundance Isotope 3) (Mass of Isotope 3) … etc.

Name three isotopes of Magnesium.

Magnesium-24, Magnesium-25, and Magnesium-26

When calculating average atomic mass, what must you do with the percent abundance?

It is easiest to change the % abundance into a decimal out of 1 (ex. 34% = 0.34)

How do you calculate the relative molecular mass of an element or compound?

Mass of one molecule of the element/compound divided by 1/12 × mass of one carbon-12 atom