The smallest particles of an element Atoms are

* The smallest particles of an element * Atoms are made up of protons, neutrons, and electrons.

n Nucleus The tiny, central core of an atom • Contains the protons and neutrons • Neutrons Protons j Fghsdfdgfsdgd sdfgfdgsfdgsfdgdfg

n Electron Cloud • Area surrounding the nucleus • Electrons are in constant motion inside this area. Neutrons Protons

1. Proton- Positive Charge ( p+ ) ~ located in the nucleus ~ Same as atomic number n 2. Neutrons-Neutral (no) Charge (n 0) n ~ located in the nucleus ~ # of neutrons = mass # - atomic # n 3. Electrons- Negative Charge ( e- ) ~ = number of protons ~Energetic particles that move all around the outside of the nucleus

26 Atomic Number Fe Element’s Symbol Element’s Name Iron 55. 847 Atomic Mass

n The number of protons in the nucleus of an atom n Every atom of a particular element contains the same number of protons n In an atom the # of protons is the same as the # of electrons

Is the average mass of one atom of the element n Atomic Mass- Atomic #= neutrons n 26 Fe Iron 55. 847 56 -26= 30 30 Neutrons in Iron!

5 B Boron 10. 8 Protons. Neutrons. Electrons. Atomic Number. Atomic Mass-

Protons. Neutrons. Electrons. Atomic Number. Atomic Mass 3 Li Lithium 6. 7

“Planetary Model” Bohr model – electrons are in specific energy levels Electron cloud model electrons are in a random cloud