Vocabulary ATOM-An atom is the smallest unit that maintains the characteristics of an element – Nucleus- The center of the atom, contains protons and neutrons – Electron Cloud –Region surrounding the nucleus containing the electrons ELEMENT- A chemical substance that is composed of atoms with the same number of protons in the nucleus

The Atom

Nucleus Protons Neutrons

eocities.com/Y osemite/Rapid s/1111/adams famsong.htm eocities.com/Y osemite/Rapid s/1111/adams famsong.htm Chorus: They are so small. (Snap, snap) They’re round like a ball. (Snap, snap) They make up the air. They’re everywhere. Can’t see them at all. (Snap, snap) 2nd Verse: Together they make gases, And liquids like molasses, And all the solid masses, The Atoms Family Chorus: They are so small. (Snap, snap) They’re round like a ball. (Snap, snap) They make up the air. They’re everywhere. Can’t see them at all. (Snap, snap) Chorus: They are so small. (Snap, snap) They’re round like a ball. (Snap, snap) They make up the air. They’re everywhere. Can’t see them at all. (Snap, snap) 1st Verse: They’re tiny and they’re teeny, Much smaller than a beany, They never can be seeny, The Atoms Family. 3rd Verse: Neutrons can be found, Where protons hang around; Electrons they surround The Atoms Family.

The Nucleus Proton-A positively charged sub-atomic particle (+). Atomic Mass=1 amu The number of protons is the same as the atomic number Li 3 7 The atomic mass The Atomic Symbol

The Nucleus Neutrons –A sub-atomic particle in the nucleus --Has a mass equal to 1 atomic mass unit --Neutron do not have a charge (0) To calculate the number of neutrons in an element… Li 3 7 The atomic number The atomic mass -The atomic number The number of neutrons

The Atom

The Electron Cloud Electrons- The number of electrons equals the number of protons Sub-atomic particle with a negative charge (-) Mass of an electron is negligible Electrons behave as if in a 3-D orbit Valence Electrons – The outer most electrons – Valence electrons are responsible for bonding

Bohr Model The first shell can have 2 electrons The second shell can have 8 electrons

Shells and the Electron Cloud

Periodic Table Groups- Arranged by the number of valence electrons Each group has similar bonding properties Periods-Arranged by increasing atomic weight Periods have the same number of shells Example:Group 1…1 valence electron Group 2…2 valence electrons Group 3…3 valence electrons Example:Period 1…1 valence shell Period 2…2 valence shells Period 3…3 valence shells

Periodic Table Periods go across on the periodic table Periods have the same number of “shells”

Periodic Table Groups go down on the periodic table Elements in the same group, have the same number of valence electrons

Let’s look at a few elements… Hydrogen 1= Proton1= electron

Let’s look at a few elements… Helium 2=protons2=neutrons 2=electrons

Let’s look at a few elements… Lithium 3=protons4=neutrons 3=electrons

Let’s look at a few elements… Fluorine 9=protons10=neutrons 9=electrons

Let’s look at a few elements… Argon 18=protons22=neutrons 18=electrons