A Little Review: The Atomic Number is equal to the # of protons, which also equals the # of electrons The Atomic Mass is calculated using the formula protons + neutrons Both protons and neutrons are found in the nucleus

protons p + neutrons n 0 electrons e - Electrons are found moving around in the cloudlike region outside of the nucleus 18 Groups (top to bottom) aka “Families” 7 Periods (right to left, like reading) 3 types of Elements Metals, Metalloids, Nonmetals

Electrons Determining Shells and Valence Electrons

Electrons are negatively charged particles that are found moving outside of the nucleus e - are 2000x smaller than p + and n 0 Electrons are found in shells Electrons in the outer most shell are called: Valence Electrons

Periods determine the # of Shells The elements in each period have the same number of shells

Groups determine Valence e - Each element in a group has the same number of electrons in their outer orbital, also known as “shells”. Exception He, it has 2 electrons

The Magic Numbers to Remember st shell can hold a max of 2e - 2 nd shell 8e - 3 rd shell 8e - … 2-8-8

Determine the number of shells and the number of valence e - for:

Determine the number of shells and the number of valence electrons for: Na is Atomic #11, p=e, so there are also 11 electrons

Name the Element: # of Shells = ________ # of Val. e- = ________ Name ______________ Symbol _____

Name the Element: # of Shells = ________ # of Val. e- = ________ Name ______________ Symbol _____

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