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LIFE IS A SERIES OF THINGS YOU’RE NOT QUITE READY FOR.

LIFE IS A SERIES OF THINGS YOU’RE NOT QUITE READY FOR. REVIEW What are the main subatomic particles that make up the atom? What is the charge on each of the particles? Which of the particles is most massive? Least massive

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LIFE IS A SERIES OF THINGS YOU’RE NOT QUITE READY FOR.

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  1. LIFE IS A SERIES OF THINGS YOU’RE NOT QUITE READY FOR.

  2. REVIEW What are the main subatomic particles that make up the atom? What is the charge on each of the particles? Which of the particles is most massive? Least massive The atomic weight of chlorine is reported as 35.5, yet no atom of chlorine has this mass. Explain.

  3. 5. How many protons, neutrons, and electrons are in the following atoms? a. 28Si b. 60Ni c. 85Rb d. 128Xe

  4. 6. Write the electron configuration for the following atoms: a. Boron, B b. Sodium, Na c. Silicon, Si d. Calcium, Ca 7. How many valence electrons does each atom in #6 have?

  5. ATOMS CAN REACT TO FORM MOLECULES (COMPOUNDS). A MOLECULE (COMPOUND) IS A GROUP OF ATOMS HELD TOGETHER BY CHEMICAL BONDS. EXAMPLE: H2O CH4 H2SO4 A GIVEN COMPOUND WILL ALWAYS HAVE THE SAME NUMBER OF EACH TYPE OF ATOMS.

  6. LAW OF DEFINITE PROPORTIONS: DIFFERENT SAMPLES OF A PURE COMPOUND ALWAYS CONTAIN THE SAME ELEMENTS IN THE SAME PROPORTION BY MASS. EXAMPLE: 9 g H2O CONTAIN 8 g O AND 1 g H 18 g H2O CONTAIN 16 g O AND 2 g H 36 g H2O CONTAIN 32 g O AND 4 g H THE RATIO IS ALWAYS 8 TO 1 (O TO H)

  7. FORMULA MASS – THE SUM OF THE MASSES OF ALL THE ATOMS IN A COMPOUND EXAMPLE: CALCULATE THE FORMULA MASS OF CaCO3 1 Ca = 40 1 C = 12 3 0 = 3 x 16 = 48 FORMULA MASS = 40 + 12 + 48 = 100

  8. PERCENT COMPOSITION: WHAT IS THE % H IN WATER, H2O? FORMULA MASS WATER, H2O = 2 H + 1 O = 2 + 16 = 18 % H = (MASS H / TOTAL MASS) X 100 = (2 / 18) X 100 = 11.1 %

  9. CALCULATE THE % CARBON IN METHANE, CH4 FORMULA MASS = C + 4 H = 12 + 4 = 16 % C = (MASS CARBON / TOTAL MASS) X 100 = (14 / 16) X 100 = 75%

  10. IN AN EXPERIMENT, 6.1 g OF Mg REACTS WITH S TO FORM 14.1 G MAGNESIUM SULFIDE. CALCULATE THE % MAGNESIUM.

  11. IONS AND IONIC COMPOUNDS One way atoms can form chemical compounds is through the loss and gain of electrons. Note: “the nucleus of an atom is unchanged in chemical processes, but atoms can readily lose or gain electrons.” - Brown and LeMay- If an atom is neutral to begin with, it becomes electrically charged if it loses or gains electrons. The resulting charged particles are called ions.

  12. Keep in mind the “octet rule” when talking about bonding. A full outer shell represents a stable configuration. If the first shell is the outer shell, it can hold 2 electrons. In any other shell, 8 is the maximum number of electrons that can exist in the outer shell. Let’s consider the reaction between sodium and chlorine: Na + Cl --> Na+Cl- Sodium loses and electron to become a sodium ion with a positive charge. Na (1s22s22p63s1) --> Na+ (1s22s22p6) + e- Positive ions are called cations. 8 electrons in outer shell

  13. Chlorine gains an electron. Cl (1s22s22p63s23p5) + e- --> Cl- (1s22s22p63s23p6) Note: negative ions are called anions. Or Na --> Na+ + e- Cl + e- --> Cl- Adding the two equations Na + Cl --> Na+Cl- Note: the net charge on an ion is represented with a superscript. 8 electrons in outer shell

  14. Give the chemical symbols, including mass numbers for the following ions: An ion with 22 protons, 26 neutrons, and 19 electrons. The ion of sulfur that has 16 neutrons and 18 electrons. The ion of selenium with 34 protons and 36 electrons

  15. In predicting the charge on a simple ion, a good rule of thumb is that atoms gain or lose electrons to end up with the same number of electrons as the nearest noble gas on the periodic table. a. Group I ions (alkali metals) have +1 charges. b. Group 2 ions (alkaline earth metals) have +2 charges. c. Group 6 ions (nonmetals) have -2 charges. d. Group 7 ions (halides) have -1 charges. e. There is no simple way to predict the charges of the transition metals.

  16. Another way of expressing the rules is that metals will usually react by losing electrons, and nonmetals will react by gaining electrons.

  17. Although we write the formulas for ionic compounds as the simple formulas, for example, NaCl (the simplest whole number ratio), ionic compounds usually exist as three dimensional solids. Using sodium chloride as an example

  18. Some characteristics of ionic compounds: They are solids at room temperature. They are held together by electrostatic forces of attraction between oppositely charged ions. They have very high melting points. All ionic compounds form crystals. Ionic substances are hard, brittle solids. When dissolved in water, the solutions are good conductors of electricity.

  19. Ions in water.

  20. NAMING IONIC COMPOUNDS Cations formed from metal atoms take the name of the metal. Na+ - sodium ion Ca+2 - calcium ion Al+3 - aluminum ion In the case of transition metal ions that can form ions of different charges, the charge is given as a Roman numeral. Fe+2 - iron (II) ion Fe+3 - iron (III) ion

  21. Anions formed from single nonmetal ions have names formed by replacing the ending of the name of the element with -ide. Br- - bromide ion Cl- - chloride ion S-2 - sulfide ion N-3 - nitride ion A few simple polyatomic anions also take the -ide ending. OH- - hydroxide ion CN- - cyanide ion O2-2 - peroxide ion

  22. To name compounds, you combine the name of the cation (first) with the name of the anion, dropping “ion”. Examples: NaCl sodium chloride BaF2 barium fluoride (note: charges have to balance) NaCN sodium cyanide KOH potassium hydroxide AgCl silver chloride FeCl2 iron (II) chloride FeCl3 iron (III) chloride

  23. There are some polyatomic anions that you will just have to learn the names. NO3- nitrate ion NO2- nitrite ion SO4-2 sulfate ion SO3-2 sulfite ion CO3-2 carbonate ion PO4-3 phosphate ion There is one polyatomic cation you need to know the name. NH4+ ammonium ion

  24. We use the names of these polyatomic anions in naming our compounds. Na2SO4 - sodium sulfate (again, charges have to balance) NaHCO3 - sodium hydrogen carbonate KNO3 - potassium nitrate BaSO4 - barium sulfate Ca(NO2)2 - calcium nitrite Li3PO4 - lithium phosphate NH4Cl - ammonium chloride

  25. COMMON LAB EQUIPMENT Evaporating dish Beaker Erlenmeyer flask Graduated cylinder Test tube Funnel Filter paper Test tube clamp Volumetric flask Ring stand Ring support Wire gauze

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