Size & Mass of Atoms Flashcards

All 6 cards in this deck

What is the radius of an atom?

About $0.1$ nm, which is $1 \times 10^{-10}$ m.

How does the radius of the nucleus compare with the radius of the atom?

The nucleus is less than $\frac{1}{10\,000}$ of the radius of the atom (about $1 \times 10^{-14}$ m).

What is the mass number of an atom?

The sum of the protons and neutrons in the atom.

What are isotopes?

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

True or false? Isotopes of the same element react chemically in the same way.

True. They have the same number of electrons and so the same electronic structure.

What are the steps to find the number of electrons in an ion?
e.g. $O^{2-}$, atomic number 8

1. Electrons in the atom = atomic number = 8.
2. A negative charge means electrons gained; a positive charge means electrons lost.
3. Adjust: $8 + 2 = 10$ electrons.