Chemistry Chapter 7

1. Chemistry Chapter 7

2. Valence electrons • an electron in the highest occupied energy level of an atom

3. To find the number of valence electrons in an atom of a representative element, simply look at its group number.

4. Electron dot structures • a notation that depicts valence electrons as dots around the atomic symbol of the element; the symbol represents the inner electrons and atomic nucleus; also called Lewis dot structure

6. octet rule • atoms react by gaining or losing electrons so as to acquire the stable electron structure of a noble gas, usually eight valence electrons

7. Atoms of the metallic elements tend to lose their valence electrons, leaving a complete octet in the next lowest energy level. Atoms of some nonmetallic elements tend to gain electrons or to share electrons with another nonmetallic element to achieve a complete octet.

8. An atom’s loss of valence electrons produces a cation, or a positively charged ion

12. The gain of negatively charged electrons by a neutral atom produces an anion

15. halide ions. • a negative ion formed when a halogen atom gains an electron

20. (3) How can you determine the number of valence electrons in an atom of a representative element

21. (3) Look up the number of that element.

22. (4) Atoms of which elements tend to gain electrons? Atoms of which elements tend to lose electrons

23. (4) Atoms of nonmetalic elements tend to gain electrons: atoms of metallic elements tend to lose electrons.

24. (5) How do cations form

25. (5) When an element loses valence electrons

26. (6) How do anions form

27. (6) When an atom gains valence electrons

28. (7) How many valence electrons are in each atom? • (a) potassium • (b) carbon • (c) magnesium • (d) oxygen

29. 7. • (a) potassium (1) • (b) carbon (4) • (c) magnesium (2) • (d) oxygen (6)

30. (8) Write the electron dot structure for each element in Question 7.

31. (8) write on board

32. (9) How many electrons will each element gain or lose in forming an ion? • (a) calcium (Ca) • (b) fluorine (F) • (c) aluminum (Al) • (d) oxygen (O)

33. (9) How many electrons will each element gain or lose in forming an ion? • (a) calcium (Ca) Lose 2 • (b) fluorine (F) Gain 1 • (c) aluminum (Al) Lose 3 • (d) oxygen (O) Gain 2

34. (10)Write the name and symbol of the ion formed when • a potassium atom loses one electron. • a zinc atom loses two electrons. • a fluorine atom gains one electron.

35. (11) Write the electron configuration of Cd 2+.

36. ionic compounds. • a compound composed of positive and negative ions (7.2)

37. Although they are composed of ions, ionic compounds are electrically neutral

38. ionic bonds. • the electrostatic attraction that binds oppositely charged ions togethe

41. chemical formula • an expression that indicates the number and type of atoms present in the smallest representative unit of a substance

42. formula unit • the lowest whole-number ratio of ions in an ionic compound; in magnesium chloride, the ratio of magnesium ions to chloride ions is 1:2 and the formula unit is MgCl2

45. Most ionic compounds are crystalline solids at room temperature

46. Ionic compounds generally have high melting points.