electron cloud

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

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

3. O O S O O H H Interpretation of a Chemical Formulas 1 molecule of sulfuric acid H2SO4 Two atoms of hydrogen Four atoms of oxygen One atom of sulfur How many hydrogen atoms are in three molecules of sulfuric acid? 3 x 2 = 6 H atoms

4. O O S O O H H Interpretation of a Chemical Formulas 1 molecule of sulfuric acid H2SO4 Two atoms of hydrogen Four atoms of oxygen One atom of sulfur How many hydrogen atoms are in three molecules of sulfuric acid? 3 x 2 = 6 H atoms

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

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

7. Isotopes # of # ofatomic mass Protons neutrons number number symbol A = proton = neutron (no electrons shown) Fill in the blanks below… B

8. 11 10 5B 5B Isotopes # of # ofatomic mass Protons neutrons number number symbol A = proton = neutron (no electrons shown) 5 5 5 10 Fill in the blanks below… 5 6 5 11 B What’s the hyphen notation for A? boron-10

9. 11 10 5B 5B Isotopes # of # ofatomic mass Protons neutrons number number symbol A = proton = neutron (no electrons shown) 5 5 5 10 Fill in the blanks below… 5 6 5 11 B What’s the hyphen notation for A? boron-10

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

11. + + + + + Carbon-14 Carbon-12 + Neutrons 6 Protons 6 Electrons 6 Neutrons8 Protons 6 Electrons 6 + + + + + + Let’s compare carbon-12 & carbon-14 How many neutrons are in carbon-14? 8 n Electrons Electrons Nucleus Nucleus

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

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

14. Isotopes – reviewHow many neutrons in chlorine-37?20n • 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 • 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 mass # charge atomic # formula HOMEWORK – • #’s 29-33,38,40

17. EXAMPLES OF IONS • A magnesium atom loses two e- and becomes which cation? Mg2+ • 12 protons • 12 neutrons (usually) • 12 electrons

18. EXAMPLES OF IONS A magnesium atom loses two e- and becomes which cation? Mg2+ • 12 protons • 12 neutrons (usually) • 12 electrons

19. EXAMPLES OF IONS A chlorine atom gains one e- and becomes which anion? Cl1- • 17 protons • 18 neutrons (usually) • 17 electrons

20. EXAMPLES OF IONS A chlorine atom gains one e- and becomes which anion? Cl1- • 17 protons • 18 neutrons (usually) • 17 electrons

21. EXAMPLES OF IONS If magnesium and chloride bond together, what’s the formula of the compound they form? MgCl2 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? MgCl2 magnesium chloride… more on this next chapter 