Chemistry Note Set I / Quiz FC-2

Electrons are found in ___

electron clouds, outside of the nucleus

Electrons are so lightweight that we regularly call its weight ___

Zero ( actually 1/836 the mass of a neutron)

Where is most of the atoms weight?

the nucleus

What are elements identified by

the number of protons in its nucleus

What does the atomic number of an element indicate?

Number of protons OR number of electrons in the atom

Although all elements have a set number of protons, they do not always have the same number of

neutrons

When an atom of an element has more neutrons than protons, it is called

an isotope

Isotopes are identified by

their mass number

What is the mass number

Weight of the atom, minus electrons. Therefore, you can find the number of neutrons by subtracting the A.N from the atomic mass.

What is the atomic mass represented by

AMU (atomic mass units), usually rounded off

Bohr’s model is one way to see

the electrons in an atom

What are electrons arranged in?

energy level rings. In actual atoms these are usually clouds of crazy shapes where the electrons can be found- not their exact location.