1. Do Now: First fill in the table below. Which one of these particles is NOT counted in the mass number?0electroncloud Electron 10 In nucleus Neutron 1+1 In nucleus Proton MASS (amu) RELATIVE CHARGE LOCATION (in the atom) SUBATOMIC PARTICLE

2. Do Now: First fill in the table below. Which one of these particles is NOT counted in the mass number?0electroncloud Electron 10 In nucleus Neutron 1+1 In nucleus Proton MASS (amu) RELATIVE CHARGE LOCATION (in the atom) SUBATOMIC PARTICLE

3. 3 x 2 = 6 H atoms Interpretation of a Chemical Formulas 1 molecule of sulfuric acid H 2 SO 4 Two atoms of hydrogen One atom of sulfur of sulfur Four atoms of oxygen of oxygen H H O S O O O How many hydrogen atoms are in three molecules of sulfuric acid?

4. 3 x 2 = 6 H atoms Interpretation of a Chemical Formulas 1 molecule of sulfuric acid H 2 SO 4 Two atoms of hydrogen One atom of sulfur of sulfur Four atoms of oxygen of oxygen H H O S O O O How many hydrogen atoms are in three molecules of sulfuric acid?

5. Models of the Atom Dalton’s model (1803) Thomson’s plum-pudding model (1897) Rutherford’s model (1909) Bohr’s model (1913) Charge-cloud model (present) Dorin, Demmin, Gabel, Chemistry The Study of Matter, 3 rd Edition, 1990, page 125 Democritus’s model (400 B.C.) 1800 1805..................... 1895 1900 1905 1910 1915 1920 1925 1930 1935 1940 1945 1803 John Dalton pictures atoms as tiny, indestructible particles, with no internal structure. 1897 J.J. Thomson, a British scientist, discovers the electron, leading to his "plum-pudding" model. He pictures electrons embedded in a sphere of positive electric charge. 1904 Hantaro Nagaoka, a Japanese physicist, suggests that an atom has a central nucleus. Electrons move in orbits like the rings around Saturn. 1911 New Zealander Ernest Rutherford states that an atom has a dense, positively charged nucleus. Electrons move randomly in the space around the nucleus. 1913 In Niels Bohr's model, the electrons move in spherical orbits at fixed distances from the nucleus. 1924 Frenchman Louis de Broglie proposes that moving particles like electrons have some properties of waves. Within a few years evidence is collected to support his idea. 1926 Erwin Schrodinger develops mathematical equations to describe the motion of electrons in atoms. His work leads to the electron cloud model. 1932 James Chadwick, a British physicist, confirms the existence of neutrons, which have no charge. Atomic nuclei contain neutrons and positively charged protons. + - - - - - e e e + + + + + + + + e ee e e e e

6. Isotopes =  atoms of the same element with different mass numbers (because they have different #’s of neutrons) Mass # Atomic # Atomic symbol: Atomic symbol: Hyphen notation: boron-11 Hyphen notation: boron-11 (protons + neutrons) (only protons)

7. = proton = neutron (no electrons shown) # of # of atomic mass Protons neutronsnumbernumber symbol A B

8. = proton = neutron (no electrons shown) # of # of atomic mass Protons neutronsnumbernumber symbol A B 555 10 5B5B 56511 5B5B boron-10 What’s the hyphen notation for A? boron-10

9. = proton = neutron (no electrons shown) # of # of atomic mass Protons neutronsnumbernumber symbol A B 555 10 5B5B 56511 5B5B boron-10 What’s the hyphen notation for A? boron-10

10. Let’s compare carbon-12 & carbon-14 + + + + + + Nucleus Electrons Carbon-12 Neutrons 6 Protons 6 Electrons6 + + + + + + Carbon-14 Neutrons ? Protons 6 Electrons6 Nucleus Electrons 8 n How many neutrons are in carbon-14? 8 n

11. Let’s compare carbon-12 & carbon-14 + + + + + + Nucleus Electrons Carbon-12 Neutrons 6 Protons 6 Electrons6 + + + + + + Carbon-14 Neutrons 8 Protons 6 Electrons6 Nucleus Electrons 8 n How many neutrons are in carbon-14? 8 n

12. Atomic # Mass # Carbon-12 Atomic # Mass # Carbon-14

13. 20 n Isotopes – review How many neutrons in chlorine-37 ? 20 n  Chlorine-37  atomic #: 17  mass #: 37  # of protons: 17  # of electrons: 17  # of neutrons: ??? Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

14. 20 n Isotopes – review How many neutrons in chlorine-37 ? 20 n  Chlorine-37  atomic #: 17  mass #: 37  # of protons: 17  # of electrons: 17  # of neutrons: 20 Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

15. IONS electrons  Ions are atoms that have lost or gained electrons.  An atom that loses an electron becomes a positive ion (CATION)  An atom that gains an electron becomes a negative ion (ANION)

16. REVIEW OF SUB/SUPER-SCRIPTS E charge formulaatomic # mass # HOMEWORK –  #’s 42,65-67,69 & review any old homework that was tough to get ready for tomorrow’s parking lot review!

17. EXAMPLES OF IONS 1. A magnesium atom loses two e - and becomes which cation? Mg 2+  12 protons  12 neutrons (usually)  12 electrons

18. EXAMPLES OF IONS A magnesium atom loses two e - and becomes which cation? Mg → Mg 2+ + 2e -  12 protons  12 neutrons (usually)  10 electrons

19. EXAMPLES OF IONS A chlorine atom gains one e - and becomes which anion? Cl 1-  17 protons  18 neutrons (usually)  17 electrons

20. EXAMPLES OF IONS A chlorine atom gains one e - and becomes which anion?  17 protons  18 neutrons (usually)  18 electrons Cl + e - → Cl 1-

21. EXAMPLES OF IONS If magnesium and chloride bond together, what’s the formula of the compound they form? MgCl 2 magnesium chloride… more on this next chapter

22. EXAMPLES OF IONS If magnesium and chloride bond together, what’s the formula of the compound they form? MgCl 2 magnesium chloride… more on this in chapter 5