1. Atoms to Molecules

2. Atomic Size Atoms are unbelievably tiny. How tiny? Incredibly smaller than plant and animal cells. Billions of atoms make up the writing tip of your pen or pencil.

3. Atom Characteristics All matter (stuff with mass and volume) is made of atoms. Space (without any particles) has no atoms. Atoms are made of smaller particles : protons (+), neutrons ( ), and electrons (-). Protons, neutrons, and electrons, of course, are made of even smaller particles…

4. Sub-subatomic particles Protons, electrons and neutrons are made of even smaller particles including, Quarks, bosons, fermions, mesons, and so on. Particle physics studies these entities.

5. Protons Positvely charged Equals the atomic number of an atom. Always stays the same for an element. Located in the nucleus of the atom.

6. Neutrons Neutral charge Atonmic mass minus the atomic number equals the number of neutrons. Different isotopes have different numbers of neutrons. Always in the nucleus.

7. Electrons N egative electrical charge Electrons equal protons in atoms. Missing electrons make positive ions. Extra electrons make negative ions. Located in shells outside nucleus.

8. Radioactivity Most elements give off neutrons or protons spontaneously into space at high speeds. Alpha Particle = 2 protons and 2 neutrons Beta Particle = electron Gamma Ray = electromagnetic wave. All three types of radiation are ionizing (dislodge electrons and cause chemical reactions to happen)

9. Radiation Types

10. Ions When an atom loses or gains an electron, it is called an ion. Ions attract oppositely charged ions. For example, sodium has 11 protons and 11 electrons. When it loses an electron, it becomes an ion with a +1 charge, Na +1

11. Other Ions Chlorine has 17 protons and 17 electrons. When it steals sodium’s electron, it will have 18 electrons, and becomes an ion with a –1 charge. Cl -1 Na +1 Cl -1 Sodium and chlorine bond to each other to become a molecule of sodium chloride.

12. Molecules Like sodium chloride, a molecule is any two atoms which bond together. Other examples include H 2 O, CO 2, and O 2

13. Molecules There are two types of bonding. Ionic bonding occurs with a metal and a nonmetal. Covalent bonding occurs when two nonmetals bond together.

14. Bonding Ionic bonds have stronger forces holding them together, so they result in higher boiling points. Covalent bonds share electrons. They are weaker bonds than ionic forces and covalent compounds have lower boiling points.

15. H 2 O – with covalent bonds

16. Ionic Bonds NaCl CaCl 2

17. The End