Chemical Bonding Review Answers to Study Guide

1. How is a compound different from a mixture? Give an example of each. Compound – chemically bonded together (salt, sugar, water, carbon dioxide) Mixture – not bonded (soup, pizza, salad, tea, salt water, air) 2. What is a chemical bond? Force that holds a compound together 3. Why does carbon form 4 bonds? Needs 4 more valence electrons (in group 14, has 4, needs 4) 4. Why does sugar have a lower melting point than salt? (think about the structure…ionic vs covalent compounds) Sugar is molecular (covalent) and the individual molecules aren’t attracted to one another. Salt is a network structure, a crystal (ionic) and all the positives are attracted to all the negatives (sort of like a box of magnets). It takes a lot of energy (heat) to break apart a network structure and make it melt.

5. What happens to the electrons when sodium and chlorine combine? Sodium transfers an electron to chlorine 6. What happens to the electrons when 2 oxygen atoms combine? They share 2 pairs of electrons 7. Which element is found in all organic compounds? Carbon 8. What type of bond is found in organic compounds? Covalent 9. List the monomer for each type of polymer and the function for each: Protein - amino acid, structure Carbohydrate - sugar (glucose), energy source DNA - nucleotide, genetic makeup

10. Which type of compound forms from a tight network of oppositely charged ions? Give an example. Ionic, salt (NaCl) 11. How many valence electrons does an atom need in order to be most stable? (HINT: It’s called the OCTET rule…) 8 12. What can atoms do to become stable (to get the right number of valence electrons)? Gain, lose, or share 13. Explain what happens to calcium and bromine atoms when they combine chemically to form calcium bromide. (Specifically…what charge to they obtain?) Calcium loses electrons and becomes positive. Bromine gains an electron and becomes negative. The positive and negative are attracted to each other. 14. Ionic compounds generally form between which types of elements? A metal and a nonmetal

15. Which pair of elements will form an ionic bond? Mg and O 16. Why are atoms in an ionic compound attracted to each other? They are oppositely charged. 17. The formation of an ionic bond involves the transfer of _____________. Electrons 18. Why don’t noble gases form chemical bonds to become stable? They already have 8 valence electrons and are stable. 19. What causes the atoms in a covalent bond to be held together? They are sharing electrons.

20. Which type of bond forms when atoms share electrons? Covalent 21. Which subatomic particle is shared or transferred when atoms react? Electrons 22. Carbon atoms are special and can link themselves together to form long chains and rings. What kind of bond do the carbon atoms form? 23. In the compound HgCl2, what does the subscript 2 mean? There are 2 chlorine atoms in the compound. 24. What type of elements form molecular (covalent) compounds? Two nonmetals (Close together on the periodic table)

25. Bromine forms a binary ionic compound with lithium 25. Bromine forms a binary ionic compound with lithium. What is the formula for this compound? LiBr (Remember…write the positive symbol with the charge, write the negative symbol with the charge, then crisscross the numbers). 26. What happens to the properties of atoms when they form compounds? Stay the same or change?? (HINT: Is it changing into a new substance?) Change 27. What is the force that holds atoms together in a compound and is formed when atoms lose, gain or share electrons with other atoms? Chemical bond 28. Which group on the periodic table is already stable and so rarely forms compounds? Noble gases, group 18

29. When an atom gains or loses electrons and becomes a charged particle, what is it called? Ion 30. What does it mean for a compound to be crystalline? (Which type of bond does it have?) Ionic bond, network of charges, high melting point 31. What does it mean for a compound to be molecular? (Which type of bond does it have?) Covalent, individual molecules, low melting point

***Make sure to go back to your notes and look at how to name compounds and write the formulas!! Ionic compounds – do not use prefixes in name, when writing formulas crisscross the charges Covalent compounds – do use prefixes in name, when writing formulas use the prefixes in the name to determine the subscripts I’m glad that you are getting these answers, but remember, unless you actually spend time studying and learning the information it will not help you on the test!!!! STUDY!!!!