Atomic Structure and the Periodic Table

Chapter 10 Notes

Chemical Symbols

Chemical symbol – an abbreviated way to write the name of an element.-example: Carbon – C

Proton – positively charged particle found in the nucleus of an atom.

Neutron – neutrally charged particle found in the nucleus of an atom.

Atomic number – the number of protons in the nucleus of an atom.

The Electron Cloud

• Electron cloud – cloud that surrounds the nucleus of an atom that describes the region in which an electron is most likely to be.– Example: students in a school

Energy Levels

• You can represent the energy differences of the electrons by picturing the atom as having different energy levels.– Example: shelves of a refrigerator door (table 10-

3)

Masses of Atoms

• Mass number = the sum of the number of protons and the number of neutrons in the nucleus of an atom.

• Number of neutrons = mass number – number of protons.

Isotopes

• Atoms of the same element that have different numbers of neutrons.

• See table 10-4 on pg. 279

Average atomic mass

• Average atomic mass = the average mass of the mixture of an element’s isotopes.– Example: boron-11

In-class Assignment

• Do pg. 281, 1-3