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Brandon Chan December 30, 2012

Chemistry Homework

52. Explain in terms of both electrons and energy, how the bright-line spectrum of an element is

produced.

Excited electrons fall to lower energy levels releasing energy as spectra. Energy is limited when an

electron falls back to lower shells.

53. Identify all elements in the mixture.

Lithium and strontium.

54. State the total number of valence electrons in a cadmium atom in the ground state.

2 valence electrons

57. Estimate the ionic radius of strontium

117pm (+/-2pm)

58. State the trend in ionic radius as the elements in Group 2 are considered in order of increasing atomic

number.

As atomic number rises, ionic radius decreases.

59. Explain, in terms of electrons why the ionic radius of a Group 2 Element is smaller than its atomic

radius.

Group 2 ions have lost an energy level of electrons, and they have 2 less electrons.

41. Which diagram represents a physical change? Only?

(1)

1. Which Choice below has no charge?

2. What is the atomic number of an oxygen atom that contains eight protons, eight neutrons, and eight

electrons?

(1) 8

3. The gold foil experiment led to the conclusion that each atom in the foil was composed mostly of

empty space because most alpha particles directed at the foil.

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(1) Passed through the foil

4. An atom of an element has a total of 19 electrons. An ion of this element has a total of 18 electrons.

Which statement describes the charge and radius of an ion?

5. Which electron configuration represents an atom in an excited state?

6. Which two particle diagrams represent mixtures of diatomic elements?

7. What information is necessary to determine the atomic mass of the element chlorine?

8. An element with an electron configuration of 2-6 will form.

9. The light emitted from a light bulb or neon light is produced when electrons in an excited state

10. Which statement is true what comparing 18O and 16O-2?

11. Which element has the least attraction for electrons in a chemical bond?

12. At STP, both diamond and graphite are solids composed of carbon atoms. These solids have

13. An element that is a good conductor of heat and electricity could have an atomic number of

14. Magnesium and Calcium ha e similar chemical properties because they have the same

15. Which atom in the ground state requires the least amount of energy to remove its valence electron?

16. All of the following atoms are likely to gain electrons except

17. Which characteristics both generally decrease when the elements in Period 3 on the Period Table are

considered in order from left or right?

18. Which element below has the greatest metallic character?

19. Which statement explains why sulfur is classified as a Group 16 element?

20. Which of the following elements has the greatest density?

21. Given the balanced equation representing a reaction:

22. Two categories of compounds are

23. The chemical bonding in sodium sulfate, na2so4 is classified as

24. Which compound is expected to have double bonds which are covalent in nature?

25. Which Lewis electron-dot diagram represents calcium oxide?

26. What is the chemical formula of iron (III) sulfide?

27. The high melting point of sodium chloride is due to

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28. Which formula represents an ionic compound?

29. Why is a molecule of C02 nonpolar even though the bonds between the carbon atom and the oxygen

atoms are polar?

30. At standard pressure, a certain compound has a low boiling point and is insoluble in water. At STP,

this compound most likely exists as

31. Which substance cannot be decomposed by a chemical change?

32. Which sample of matter can be separated into different substances by physical means?

33. According to the kinetic molecular theory, the molecules of an ideal gas

34. Under which conditions of temperature and pressure would a real gas behave most like an ideal gas?

35. The graph below represents the relationship between temperature and time as heat is added to a

sample of ice at -100 degrees Celsius?

36. The temperature of a sample of matter is a measure of the

37. At STP, which sample of matter has molecules spread furthers apart?

38. Which temperature would cause a sample of an ideal gas to double in volume while the pressure is

held constant?

39. When a 15 gram sample of water is heated from 20 degrees Celsius to 60 degrees Celsius?