1. Chemistry Chapter 8

2. covalent bond • a bond formed by the sharing of electrons between atoms

3. molecule • a neutral group of atoms joined together by covalent bonds

4. diatomic molecule • a molecule consisting of two atoms

5. molecular compound • a compound that is composed of molecules

6. Molecular compounds tend to have relatively lower melting and boiling points than ionic compounds.

8. molecular formula • a chemical formula of a molecular compound that shows the kinds and numbers of atoms present in a molecule of a compound

9. A molecular formula shows how many atoms of each element a molecule contains

14. (1) Key Concept How are the melting points and boiling points of molecular compounds usually different from ionic compounds

15. (2) Key Concept What information does a molecular formula provide?

16. (3)What are the only elements that exist in nature as uncombined atoms? What term is used to describe such elements?

17. (4)Describe how the molecule whose formula is NO is different from the molecule whose formula is N2O.

18. (5)Give an example of a diatomic molecule found in Earth’s atmosphere

19. (6)What information does a molecule’s molecular structure give?

20. 1.Molecular compounds tend to have relatively A.low melting points and high boiling points.B.low melting points and low boiling points.C.high melting points and high boiling points.D.high melting points and low boiling points.

21. 2.A molecular formula shows A.how many atoms of each element a molecule contains.B.a molecule's structure.C.which atoms are bonded together.D.how atoms are arranged in space.

22. 3.A molecule consisting of two atoms is called a A.two atom molecule.B.monatomic molecule.C.biatomic molecule.D.diatomic molecule.

23. In forming covalent bonds, electron sharing usually occurs so that atoms attain the electron configurations of noble gases.

24. single covalent bond • a bond formed when two atoms share a pair of electrons

26. An electron dot structure such as H:H represents the shared pair of electrons of the covalent bond by two dots.

27. structural formula • a chemical formula that shows the arrangement of atoms in a molecule or a polyatomic ion; each dash between a pair of atoms indicates a pair of shared electrons

29. unshared pair • a pair of valence electrons that is not shared between atoms

39. Atoms form double or triple covalent bonds if they can attain a noble gas structure by sharing two pairs or three pairs of electrons.

40. double covalent bond • a bond in which two atoms share two pairs of electrons

41. triple covalent bond • a covalent bond in which three pairs of electrons are shared by two atoms

47. coordinate covalent bond • a covalent bond in which one atom contributes both bonding electrons

48. In a coordinate covalent bond, the shared electron pair comes from one of the bonding atoms

49. polyatomic ion • a tightly bound group of atoms that behaves as a unit and has a positive or negative charge