Honors Chemistry Atoms Unit WCHS Mrs. Herrick

Electron symbol, location in an atom, & electric charge

Symbol: e-

Location: Moving outside the nucleus

Electric charge: -

Proton symbol, location in an atom, & electric charge

Symbol: p

Location: Nucleus

Electric charge: +

Neutron symbol, location in an atom, & electric charge

Symbol: n

Location: Nucleus

Electric charge: N/A

Overall electric charge of an atom

Neutral— no overall electric charge

What values must be the same in the nucleus of an atom?

An atom must have as many electrons as there are protons

Atomic number (Z)

The number of protons in the nucleus of an atom

Mass Number (A)

The sum of the protons and neutrons in the nucleus 

Isotope

An atom with the same number of protons, but a different number of neutrons— meaning that isotopes of the same element have the same atomic number but a different mass number

What type of notation is this?

Symbolic notation

In this type of notation, what values go on the top and bottom?

Mass number (A) goes on the top, and atomic number (Z) goes on the bottom 

What is this type of notation?

Hyphenated notation

In this type of notation, what is the value represented?

The mass number (A)

What are ions?

Atoms with unequal values of protons and electrons

In an ion, what value is changing?

The number of electrons— the atomic number (which is also the number of protons) does not change

What is a negative ion?

An ion where the atom gained electrons, making it negative, or an anion

What is a positive ion?

An ion where the atom lost electrons, making it positive, or a cation

What do two isotopes always have a different number of?

Mass number & the number of neutrons