Matter & The Atom

1. Matter &The Atom

2. Matter The term matter describes all of the physical substances around us Matter is anything that has mass and takes up space The Universe is made up of matter and energy

3. *Matter is made up of atoms.*An atom is the smallest whole particle of matter.* Sub-Atomic particles are smaller than atoms and are the tiny particles that an atom is made of.

4. Early Models of the AtomRutherford • Mostly empty space • Small, positive nucleus • Contained protons • Negative electrons scattered around the outside

5. Early Models of the AtomBohr • Electrons move in definite orbits around the nucleus

6. Modern Model of the AtomThe electron cloud • Sometimes called the wave model • Spherical cloud of varying density • Varying density shows where an electron is more or less likely to be

7. Atomic Structure • Nucleus • Protons • Neutrons • Electrons

8. Atomic Structure • Electrons • Tiny, very light particles • Have a negative electrical charge (-) • Move around the outside of the nucleus

9. Atomic Structure • Protons • Much larger and heavier than electrons • Protons have a positive charge (+) • Located in the nucleus of the atom

10. Atomic Structure • Neutrons • Large and heavy like protons • Neutrons have no electrical charge • Located in the nucleus of the atom

11. Atomic Structure

12. Describing Atoms • Atomic Number = number of protons • In a neutral atom, the # of protons = the # of electrons • Atomic Mass= the number of protons + the number of neutrons

13. Ions • An atom that carries an electrical charge is called an ion • If the atom loses electrons, the atom becomes positively charged (because the number of positively charged protons will be more the number of electrons) • If the atom gains electrons, the atom becomes negatively charged (because there are more negative charges than positive)

14. Ions • The number of protons does not change in an ion. • The number of neutrons does not change in an ion. • So, both the atomic number and the atomic mass remain the same.

15. Ions This atom has lost an electron. Now it has one more proton than electron. One more proton means one more positive charge. This makes the total charge of the atom POSITIVE. This atom has gained an electron. Now it has one less proton than electron. One less proton means one less positive charge. This makes the total charge of the atom NEGATIVE.

16. Isotopes • The number of protons for a given atom never changes. • The number of neutrons can change. • Two atoms with different numbers of neutrons are called isotopes • Isotopes have the same atomic # • Isotopes have different atomic Mass #’s

17. Isotopes