4. A hydrogen bond is formed between a hydrogen atom and a negative atom, usually a nitrogen or oxygen.

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1 Name Biology Summer Assignment Print, complete and bring this assignment with you on the first day of classes. Use the background information document to help you complete this assignment. Modified True/False Indicate whether the statement is true or false by writing the word True or the word False on the left line provided. If false, change the identified word or phrase to make the statement true. 1. A substance made up of only one kind of atom is an element. _ 2. Adhesion is the attraction between molecules of the same substance, for example the fact that a water molecule is attracted to other water molecules. 3. A substance with equal numbers of ions and ions is a basic solution. _ 4. A hydrogen bond is formed between a hydrogen atom and a negative atom, usually a nitrogen or oxygen. _ 5. The basic unit of matter is the molecule. _ 6. Buffers are weak acids or bases that can react with strong acids or bases to prevent sudden changes in ph. _ Multiple Choice Identify the choice that best completes the statement or answers the question by writing the capital letter on the left line provided. 1. What type of electron is available to form bonds? a. ionic c. covalent b. valence d. nucleus 2. Which of the following statements about a compound is true? a. The physical and chemical properties of a compound are usually the same as those of the elements from which it is formed. b. Only the chemical properties of a compound are usually the same as those of the elements from which it is formed. c. Only the physical properties of a compound are usually the same as those of the elements from which it is formed. d. The physical and chemical properties of a compound are usually very different from those of the elements from which it is formed. 3. In a covalent bond, two atoms share electrons. This type of bonding _ a. allows atoms to always share electrons equally. b. is easily broken. c. occurs only between different elements. d. helps to fill electron shells. 1

2 4. In a water molecule, shared electrons spend more time around the oxygen atom than the hydrogen atoms. As a result, the oxygen atom is _ a. slightly negative. c. very negative. b. very positive. d. slightly positive. 5. If an atom or a molecule gains or loses an electron, it becomes a(n) _ a. molecule. c. ion. b. isotope. d. different element. 6. The three subatomic particles that make up atoms are _ a. positives, negatives, and neutrals. c. protons, neutrons, and electrons. b. protons, neutrons, and isotopes. d. neutrons, isotopes, and electrons. Figure If there were eight neutrons in the nucleus of the Figure diagram, how would it be related to the original? a. Its charge would increase. c. It would be an isotope form. b. It would be a molecule. d. Its charge would decrease. 8. If one of the black dots in the Figure diagram was lost during a reaction, the charge of the atom would _ a. be neutral. c. be negative. b. be positive. d. remain the same. 9. A map of eastern North America, showing the ph of rainfall in the various states, indicates that the ph of rain in New York State varies from 4.22 to According to these figures, the most acidic rainfall in New York State has a ph of a c b d Water molecules are polar, with the _ a. oxygen side being slightly positive and the hydrogen side being slightly negative. b. oxygen and hydrogen sides being slightly positive. c. oxygen side being slightly negative and the hydrogen side being slightly positive. d. oxygen and hydrogen sides being slightly negative. 11. A solution is a _ a. chemical reaction. b. mixture in which the substances are evenly spread out. c. combination of isotopes. 2

3 d. mixture in which undissolved substances do not settle out. 12. When salt is dissolved in water, water is the _ a. reactant. c. solvent. b. solute. d. solution. 13. Solutions that have more OH than H + ions are _ a. enzymes. c. neutral. b. bases. d. acids. 14. Which of these foods had the greatest concentration of H + ions? a. apple, ph 2.9 c. corn, ph 6.2 b. bread, ph 5.5 d. milk, ph A covalent bond is formed as the result of _ a. sharing protons. c. transferring protons. b. sharing electrons. d. transferring electrons. 16. An ionic bond is the result of _ a. transfering protons c. sharing electrons unevenly b. sharing electrons evenly d. transfering electrons 17. If an atom contains 11 protons and 12 neutrons, its atomic number is _ a. 11. c. 23. b. 1. d What type of ion forms when an atom gains electrons? a. negative c. radioactive b. positive d. neutral 19. If an atom contains 3 protons, 4 neutrons, and 3 electrons, its mass number is _ a. 7. c. 4. b. 10. d Isotopes are atoms of the same element with the same number of protons and a different number of _ a. electrons. c. protons. b. ions. d. neutrons. 21. Which of the following makes up a molecule of water? a. two atoms of hydrogen and one atom of oxygen b. one atom of hydrogen and one atom of oxygen c. one atom of hydrogen and two atoms of oxygen d. one atom of sodium and one atom of chlorine 22. What are found in the space surrounding the nucleus of an atom? a. ions c. electrons b. neutrons d. protons 23. Nonpolar covalent bond is formed by the _. a. transfer of electrons c. equal sharing of electrons b. sharing of protons d. unequal sharing of electrons 24. What type of ion forms when an atom gains electrons? a. negative c. possibly negative or positive b. positive d. neutral 25. Which of the following terms describes a substance formed by the combination of two or more elements in definite proportions? a. enzyme c. isotope b. compound d. nucleus 26. Isotopes are atoms of the same element with a different number of _. 3

4 a. electrons c. protons b. ions d. neutrons Figure Which property of water causes the meniscus shown in Figure 2 1? a. ph c. cohesion b. adhesion d. heat capacity 28. A substance made up of only one kind of atom is a(n) _. a. element c. molecule b. compound d. ion 29. _ are found in the nucleus of an atom. a. Neutrons c. Protons and neutrons b. Protons d. Protons and electrons 30. A chemical bond formed by the transfer of electron is a(n) _. a. covalent bond c. ionic bond b. hydrogen bond d. van der Waals forces 31. What type of ion forms when an atom loses electrons? a. neutral c. negative b. positive d. radioactive 32. Solutions that contain concentrations of H + ions lower than pure water _. a. have ph values below 7 c. are bases b. are acids d. are enzymes 33. A description for the formula H 2O is two _ a. molecules of hydrogen and one atom of oxygen. b. molecules of oxygen and one molecule of hydrogen. c. atoms of hydrogen and one atom of oxygen. d. atoms of oxygen and one atom of hydrogen. 34. On the Periodic Table, what is the symbol for oxygen? a. O c. o b. Ox d. On 35. On the Periodic Table, P is the symbol for _. a. phosphorus c. lead b. potassium d. iron 4

5 Periodic Table Chart Fill in the missing components of the table using the information provided. 1. Element Name/ Symbol Atomic Number Mass Number Number of Protons Number of Neutron Number of Electrons Beryllium (Be) 9 4 Aluminum (Al) Potassium (K) Calcium (Ca +2 ) Nitrogen (N -3 ) 7 15 Bromine (Br -1 ) Magnesium (Mg-26) Chlorine (Cl-37) Short Answer Write the answers to the following questions in the space provided. Make sure handwriting is legible! 1. List the 3 subatomic particles of an atom, include the charge of each particle and where each particle is located within the atom. 2. What is the main similarity and the main difference between a polar covalent bond and a nonpolar covalent bond? 5

6 Science Skills Use the figure below to answer the following questions. Write the answer on the line provided. ph Values of Some Common Substances Substance ph Hydrochloric acid 1.0 Sulfuric acid 1.2 Tomatoes 4.2 Rainwater 6.2 Pure water 7.0 Sea water 8.5 Ammonium chloride 11.1 Sodium hydroxide 13.0 Figure Apply Concepts What is the strongest acid listed in Figure 2 5? _ 2. Apply Concepts What is the ph of the weakest acid listed in Figure 2 5? _ 3. Apply Concepts What is the ph of the strongest base listed in Figure 2 5? 6