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Quiz 2.1

Quiz 2.1. According to Thompson’s Plum Pudding Model, what is embedded inside the entire mass of an atom? Calcium has 20 protons. If it has 22 neutrons, what are two ways to write down this specific element? If calcium has a mass number of 40, how many neutrons does it have?

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Quiz 2.1

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  1. Quiz 2.1 • According to Thompson’s Plum Pudding Model, what is embedded inside the entire mass of an atom? • Calcium has 20 protons. If it has 22 neutrons, what are two ways to write down this specific element? • If calcium has a mass number of 40, how many neutrons does it have? • If an atom has 5 protons, and 7 neutrons, and 5 electrons, what is the mass number?

  2. 2.3 Electrical Properties

  3. Electrical properties • Like charges repel • Unlike charges attract

  4. A neutral atom has the same number of protons (positive charge) and electrons (negative charge), cancelling each other out • Atoms and molecules can become electrically charged depending on the difference of protons and electrons • These electrically charged atoms are called ions. p+ e-

  5. Sodium can be found as a cation, written as Na+ • Chlorine can be found as an anion, written as Cl-

  6. Na+ has a charge of +1 • How many protons does it have? • Electrons? • Ca2+ has a charge of +2 • How many protons does it have? • Electrons?

  7. Cl-has a charge of -1 • How many protons does it have? • Electrons? • S2- has a charge of -2 • How many protons does it have? • Electrons?

  8. Molecules can be ions too. • NO3- is known as nitrate • SO42- is known as sulfate

  9. Ionic Compounds • A cation and an anion can combine to form ionic compounds • The cation, Na+, can combine with the anion, Cl-, to form the ionic compound, NaCl • KCl, CaF2, Al2O3, Na2SO4 are all examples of ionic compounds • Cations are always written first (you never write ClNa) • The negative and positive charges have to balance each other out

  10. What ionic compound is formed between Li+ and S2-? • The charges of Li+ and S2- has to balance each other. • Therefore, we need two Li+ in order to balance out one S2- 2Li+ + S2- Li2S (this is a balanced chemical equation)

  11. What ionic compound is formed between Ca2+ and S2-? Write out a balanced chemical equation. Ca2+ + S2- CaS

  12. What ionic compound is formed between Be2+ and Br-? Write out a balanced chemical equation. Be2+ + 2Br- BeBr2

  13. What ionic compound is formed between Al3+ and O2-? • The charges of Al3+and O2- has to balance each other. • Therefore, we need two Al3+ in order to balance out three O2- 2Al3+ + 3O2- Al2O3 • Two methods to solve this: 1) Lowest Common Multiple 2)Short Cut

  14. Lowest Common Multiple. Find the lowest common multiple of the charges so for Al+3 and O-2 , the LCM is 6. We need 2 Al+3 to get 6, and 3O-2 to get 6. 2) Short cut. The charge of the ion is the subscript of the opposite ion. Just make sure to simplify. 3+ 2- Al2 O3

  15. What ionic compound is formed between Al3+ and N2-? 2Al3+ + 3N2- Al2N3 • What ionic compound is formed between Ca2+and N3-? • 3Ca2+ + 2N3- Ca3N2

  16. 3Ca2+ + 2N3- Ca3N2

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