1. Slide 1 Particles in the Atom

2. Slide 2 Electrons (-) charge no mass located outside the nucleus Protons (+) charge 1 amulocated inside the nucleus Neutron no charge 1 amulocated inside the nucleus Particles in the Atom

3. Slide 3 Subatomic Particles Electron Proton Neutron NameSymbolCharge Relative mass Actual mass (g) e-e- p+p+ nono +1 0 1/1840 1 1 9.11 x 10 -28 1.67 x 10 -24

4. Slide 4 Structure of the Atom – –There are two regions The nucleus – –With protons and neutrons Positive charge Almost all the mass – –Electron cloud Most of the volume of an atom The region where the electron can be found

5. Slide 5 Subatomic Particles Most of the atom’s mass. NUCLEUSELECTRONS PROTONS NEUTRONS Negative Charge Positive Charge Neutral Charge ATOM Atomic Number equals the # of... equal in a neutral atom Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

6. Slide 6 Size of an atom Atoms are incredibly tiny. Measured in picometers (10 -12 meters) – Hydrogen atom, 32 pm radius Nucleus tiny compared to atom – Radius of the nucleus near 10 -15 m. – Density near 10 14 g/cm IF the atom was the size of a stadium, the nucleus would be the size of a marble.

7. Slide 7 Counting the Pieces Atomic Number = number of protons # of protons determines kind of atom Atomic Number = number of electrons in a neutral atom Mass Number = the number of protons + neutrons

8. Slide 8 Symbols Contain the symbol of the element, the mass number and the atomic number X Mass number Atomic number # protons + # neutrons mass number

9. Slide 9 Symbols Find the – number of protons – number of neutrons – number of electrons – Atomic number – Mass number F 19 9 9 10 9 9 19

10. Slide 10 Symbols Find the – number of protons – number of neutrons – number of electrons – Atomic number – Mass number 35 45 35 80 Br 80 35

11. Slide 11 Symbols Find the – number of protons – number of neutrons – number of electrons – Atomic number – Mass number Na 23 11 12 11 23

12. Slide 12 Symbols Find the – number of protons – number of neutrons – number of electrons – Atomic number – Mass number V 51 23 28 23 51

13. Slide 13 Symbols If an element has 60 protons and 144 neutrons what is the – Atomic number – Mass number – Number of electrons – Complete symbol 60 204 60 Nd 60 2 04