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BIOLOGY INTERACTIVE HOMEWORK CHEMISTRY PACKET KSTATE...

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Homework: Biology 198 … Chemistry for Biologists.

Name: ____________________________________

Subatomic Particles Atoms are made up of several components. Collectively, these components are called the subatomic particles. We will be discussing the three major subatomic particles … protons, neutrons, and electrons. Here is the diagram of an atom:

n P

P

nucleus

n Electron cloud

1. The protons (p) and neutrons (n) are packed together in an inner core called the __Nucleus/Core__________. 2. The outer part of the atom, which contains electrons, is called the _____Electron Cloud__________ ________.. 3. The electron cloud has a negative electrical charge. What type of electrical charge do you think the electron has? _____-1__________ 4. Remember that “like” electrical charges repel each other and that “unlike” electrical charges attract each other. Indicate whether the following pairs of charges would attract or repel each other. a. + + REPEL b.

- -

c. + d.

-

REPEL

-

ATTRACT

+

ATTRACT

5. The nucleus of an atom attracts the negatively charged electrons. Therefore, the overall charge of the nucleus must be __POSITIVE________________ (negative or positive) 6. The neutron was named for its electrical characteristics. It has no electrical charge; it is neutral. This means that the positive charge of the nucleus must be due to the second type of particle it contains. This second type of particle is the ____NEGATIVE___________. 7. So far, then, we have this picture of atomic structure. a. an atom consists of an inner part called the __NUCLEUS/CORE______________, which is made up of two particles, the _NEURONS___________ and the ____PROTONS___________. b. the electron has what type of charge? ___NEGATIVE_________

c. the proton has what type of charge? __POSITIVE___________ d. the neutron has a charge of ______NEUTRAL___________. 8. The charge of the electron balances the charge on the proton. If the electron has a charge of -1, the the proton would have a charge of _______+1____________ (-1, +1, 0) 9. An atom with one proton in its nucleus and one electron outside that nucleus would therefore have an overall charge of ___________0_______ (-1, +1, 0) 10. Atoms are electrically neutral. This means that an atom will contain (check one): _______ more protons than electrons _______ more electrons than protons X_____ an equal number of protons and electrons 11. An atom with 12 protons in the nucleus would have how many electrons outside the nucleus? 12 ________ 12. The atom with the simplest atomic structure is hydrogen. For simplicity sake, in the illustrations below we shall merely indicate the electron(s) outside the nucleus and omit the electron cloud. p

e-

hydrogen

a. the nucleus of the hydrogen atom consists of one ___PROTON__________. b. The outer part of the atom, the electron cloud, contains one ELECTRON _____________. 13.

The helium atom is a little more complicated. It contains: (how many?) 2______ neutrons 2______ protons 2______ electrons

e-

n p p n helium

e-

Atomic Number There are more than 100 known elements. Each element has 2 numbers associated with it – numbers that give certain facts about the structure of its atoms. The first number is the atomic number. This is the number of protons found in the nucleus of an atom. 14.

Hydrogen is the simplest atom and contains only 1 proton, so the atomic number of hydrogen is _1___.

15.

Uranium is the most complicated of the elements that occur naturally. A uranium atom contains 92 protons, 146 neutrons, and 92 electrons. The atomic number of uranium is ____92_________.

16.

An atom of magnesium (atomic number 12) must have a nucleus containing ___12_______ protons. If the nucleus contains 12 protons, there how many electrons must there be? __12__________

17.

Therefore, the atomic number of an element indicates the number of ____PROTONS_________ in the nucleus of the atom, and also the number of ____ELECTRONS__________ outside the nucleus.

Mass Number The second number associated with each atom is the mass number. The mass number expresses the sum of the masses of the particles in the atom. The proton has a mass of 1 atomic mass unit. An electron is so light that it is considered to have a zero mass or a mass of 0 atomic mass units. 18.

A hydrogen atom has a mass of ____1____________.

n p p en 19. The helium atom has a mass number of 4. helium a. the 2 protons in the helium atom have a total of how many atomic mass units? ____2______ b. the 2 electrons in the helium atom have a total of how many atomic mass units? ____0_____ c. therefore, for the helium to have a mass number of 4, the 2 neutrons must contain how many atomic mass units all together? _____2_______ d. If 2 neutrons have a total of 2 atomic mass units, a single neutron must have an atomic mass of _1_________. e-

20.

Because the electrons, which have practically no mass, are located outside the nucleus, the entire mass of the atom can be considere to be located where (check one)? ________ in its electron cloud ___X____ in the nucleus

21.

The atomic number indicates the number of protons (each with an atomic mass of 1) inside the nucleus of an atom. The mass number indicates the number of protons and neutrons (each with atomic mass of 1) in the nucleus. Therefore, the number of neutrons can be determined by subtracting the atomic number from the mass number. The sodium atom has a mass number of 23 and an atomic number of 11. The number of neutrons in the nucleus of the sodium atom is _______12__________.

22. The carbon atom has an atomic number of 6 and a mass number of 12. The carbon atom contains how many of each of the following? 6 protons in the nucleus 6 neutrons in its nucleus 6 electrons outside its nucleus 23. The element phosphorus has an atomic number of 15 and a mass number of 31. The phosphorus atom contains how many of each of the following? 15 protons in the nucleus 16 neutrons in its nucleus 15 electrons outside its nucleus 24. The magnesium atom has an atomic number of 12 and a mass number of 24. The magnesium atom contains how many of each of the following? 12 protons in the nucleus 12 neutrons in its nucleus 12 electrons outside its nucleus

25. If a uranium atom has 92 protons, 146 neutrons, and 92 electrons, what is ……. __238____ the mass number _92_____ the atomic number

Isotopes A carbon atom has an atomic number of 6 and a mass number of 12. This carbon atom contains how many of each of the following? 6______ protons in the nucleus 6______ neutrons in its nucleus 6______ electrons outside its nucleus. 26. Now let’s say that we found a second carbon atom. After analyzing this atom of carbon, we found that it had an atomic number of 6 and a mass number of 13. This carbon atom contains how many of each of the following? 6 protons in the nucleus 7 neutrons in its nucleus 6 electrons outside its nucleus 27. The first carbon atom is called carbon 12, and the second carbon atom is called carbon-13. By comparing their protons, neutrons, and electrons, you can see that these atoms have different mass numbers, and thus different numbers of _____NEUTRONS_______. Atoms of the same element that have different mass numbers (different numbers of neutrons) are called isotopes. 28. Isotopes may be defined as atoms that have (check one): the same atomic number and the same mass number different atomic numbers X different mass numbers and the same atomic number 29. The two isotopes of chlorine (atomic number 17) have mass numbers of 35 and 37. How many neutrons does chlorine-35 have? ________18_____ How many neutrons does chlorine-37 have? ____20_________ 30. Radioisoptopes are isotopes that give off radiation. They are frequently used in medical applications. I-131 (radioactive Iodine) is used in the diagnosis and treatment of thyroid conditions. How does I-131 (radioactive iodine) compare with I-127 (nonradioactive iodine) in the following: X atomic number mass number

Electron Energy Levels The electrons are located outside the nucleus of the atom. These electrons make up the electron cloud, which may be subdivided into different energy levels. The first energy level is nearest the nucleus. Then comes the second energy level, the third energy level, and so on. Each energy level can hold a certain maximum number of electrons. For the purpose of simplifying this information, we will say that the first energy level can hold a maximum of 2 electrons, while the second and third energy levels can hold a maximum of 8 electrons each. 31. The first energy level can hold a maximum of ____2_______ electrons. 32. Can the first energy level hold fewer than two electrons? ____YES______ 33. Can the first energy level hold more than two electrons? ___NO_______ 34. For the second energy level, the maximum number of electrons is _____8________.

35. The maximum number of electrons in the third energy level is _____8_______. 36. In the diagram below, label the maximum number of electrons possible in the three energy levels represented by dashed circles around the nucleus.

The following rules must be observed when considering the placement of electrons in the various energy levels. The first energy level must be filled with 2 electrons before electrons can go into the second energy level. 37. The second energy level must be filled with ___8____ electrons before electrons can go to the third energy level. 38. On the diagram below, show the structure of the hydrogen atom with an atomic number of 1 and a mass number of 1.

39. The number of protons in the hydrogen atom is ____1____. 40. The number of neutrons is ___0______. 41. The number of electrons is __1______. 42. The one electron in the hydrogen atom must go into which energy level (the first, second, or third?) ____FIRST 43. In the diagram below, draw the structure of the helium atom with an atomic number of 2 and a mass number of 4.

44. Now, let’s look at the structure for the lithium atom, which has an atomic number of 3 and a mass number of 7. a) the number of protons in the lithium atom is __3_________. b) the number of neutrons in the lithium atom is ___4_______. c) the number of electrons in the lithium atom is ___3_______. 45. There are 3 electrons in the lithium atom. How many energy levels will the lithium atom have? __2___ 46. Complete the diagram to the right for the lithium atom.

The carbon atom has an atomic number of 6 and a mass number of 12. a) the number of protons in the carbon atom is ______6_____. b) the number of neutrons in the carbon atom is ____6______. c) the number of electrons in the carbon atom is ____6______. d) complete the diagram to the right for the carbon atom. 47. In the element sodium, atomic number 11, there are how many electrons? ___11__ a) how many energy levels will the sodium atom have? __3_______ b) how many electrons will each energy level of the sodium atom have? _2____ first energy level ____8__ second energy level ___1____third energy level c) complete the diagram below for the sodium atom

Chemical Symbols Elements are the building blocks of the universe. They cannot be broken down into simpler substances by ordinary chemical means. Each of the >100 elements has its own name and its own properties. The symbol for an element is usually an abbreviation for its name. Frequently the abbreviation is merely the first letter of that name. The following table lists some of these elements Element Hydrogen Carbon Oxygen Nitrogen Phosphorus Sulfur

Symbol H C O N P S

48. What elements are present in water (H2O)? ____________HYDROGEN/OXYGEN_______________________ 50. What elements are present in ammonia (NH3)? ________NITROGEN/HYDROGEN_____________________________ 51. Biotin, one of the B-vitamins (C10H16O3N2S), contains which elements? CARBON/HYDROGEN/OXYGEN/NITROGEN/SULFUR 52. Adenosine triphosphate (ATP) is the body’s primary energy compound and has the formula C11H18O13N5P3 . What elements does ATP contain? CARBON/HYDROGEN/OXYGEN/NITROGEN/PHOSPHORUS

When the names of more than one element begin with the same letter, frequently the second letter of the name is added to the symbol. Note that only the first letter of the symbol is capitalized. Here are some of the elements whose symbols are the first two letters of their name. Write the symbols for each. Element Symbol Calcium Ca Bromine Br Silicon Si Barium Ba 53. CaBr2 contains which two elements? ___________calcium/bromine________________________ 54. BaO2 contains which two elements? _________barium/oxygen___________________________ 55. CaC2O4 contains which three elements? _______calcium/carbon/oxygen_______________________________________ There are several elements whose symbols are not derived from the first letter or first two letters of their English names. Some of those elements are listed in the following table. Element Symbol Chlorine Cl Sodium Na Magnesium Mg Potassium K Zinc Zn Iron Fe Which elements are present in the following? 56. KBr POTASSIUM/BROMINE__________________________________________ 57. CCl4

CARBON/CHLORINE__________________________________________

58. NaOH

SODIUM/OXYGEN/HYDROGEN_______________________________

59. MgCl2

MAGNESIUM/CHLORINE__________________________________________________________________________________

60. NaNO3 SODIUM/NITROGEN/OXYGEN_____________________________________________ 61. K3FeC6N6

_____________________________________

POTASSIUM/IRON/CARBON/NITROGEN

Atoms and Molecules One atom of hydrogen is written as H. The number 1 is understood. Two atoms of hydrogen is written as 2H. 62. Three atoms of carbon are written as 3C___________________________________. Atoms combine to form molecules. A molecule contains two or more atoms of the same or different elements. 63. The molecule O2 contains how many atoms of oxygen?2______________________ 64. Each molecule of glucose (C6H12O6) contains: __6______________ atoms of carbon ____12____________ atoms of hydrogen ____6____________ atoms of oxygen

65. A molecule of water is composed of two hydrogen atoms and one oxygen atom. Write the formula for a water molecule. H20___________________________________________________ 66. A molecule of sucrose contains 12 atoms of carbon, 22 atoms of hydrogen, and 11 atoms of oxygen. The formula for sucrose is C12H22O11_______________________________________. When you want to represent more than 1 molecule of a compound, the number of molecules precedes the symbols. 67. Thus, 6CO2 indicates how many molecules of carbon dioxide?_________________6 68. How would eight molecules of water be represented?_________________________8H2O

Ionization Atoms contain equal numbers of protons and electrons. 69. Thus, atoms are (check one) _____electropositive neutral

_____electronegative

__X___electrically

70. The electron is a ___NEGATIVELY_________ (negatively/positively) charged particle. So, if an atom loses an electron, it will than have an overall ______POSITIVE______ (negative/positive) charge. 71. If an atom were to gain an electron, it would then have an overall ___NEGATIVE________ charge.

An ion is an atom that has acquired an electrical charge by either losing or gaining an electron. Note that electrons, which are located outside the nucleus in the electron cloud, are lost or gained in the formation of ions. The nucleus, which contains protons and neutrons, does not take part in the formation of ions. 72. If a hydrogen ion loses its electron, it becomes a hydrogen ion. Because it loses an electron, it is a POSITIVELY______________ (negatively/positively) charged ion. 73. Any atom that has lost or gained an electron is called an __ION____________. 74. If an atom gains an electron, it becomes a ___NEGATIVELY____________ charged ion. 75. If an atom loses an electron, it becomes a __POSITIVELY_____________ charged ion. Some elements reach their most stable state when their outermost electron shell (energy level). This outermost electron shell is called the valence shell. 76. This atom of helium (shown to the right) contains 2 electrons, which fill the first energy level So, in this example, the first energy level is also called the ____VALENCE SHELL_________________________.

2p 2n

2e-

77. Helium (He) has a completed valence shell, one that can hold no more electrons. Thus, helium is a very __STABLE______________ (stable/unstable) atom. Such elements are usually unreactive.

Most atoms reach their most stable state when they have 8 electrons in their outer energy level. 78. The atom of neon (Ne) shown on the right contains 10 electrons. Two of the electrons fill the first energy level and the remaining 8 electrons are in the second energy level. So, the second energy level of neon would be called its ____VALENCE SHELL___________________.

10p 10n

2e8e-

79. Look at the atom of chlorine on the right. In chlorine, the outer energy level, or ELECTRON SHELL______________________________ is the ___THIRD_______________ (first/second/third) energy level. It contains 7 electrons. Thus, to attain a stable state, the chlorine atom needs to gain how mnay electrons? _____1_______________ 2e80. Suppose that an atom of chlorine gains the one electron it needs to become 17p stable. Because it has gained an electron, it is now a charged atom, called an 8e18n ____ION___________. Would it have a positive or negative charge? 7e__NEGATIVE_________ 81. Which of the following symbos stands a chloride ion that has gained 1 electron? ____ Cl _____Cl+ ___X___ Cl82. If the chlorine atom is to gain an electron, some other atom must lose the electron. a. The atom that loses the electron could be sodium, the symbol for which is 11p _____Na________. 12n b. The sodium atom (shown on the right) has how many electrons in its valence shell? __11____ c. To become stable, this sodium atom will have to ____gain_____ (gain/lose) one electron. d. When the sodium atom loses 1 electron, it becomes a _____POSITIVELY_________ (positively/negatively) charged _ION_________.

2e8e1e-

The reaction between sodium and chlorine can be written as Na + Cl  Na+ + Cl83. When a sodium atom reacts with a chlorine atom, the sodium atom ____GAINS (gains/loses) one electron to form a sodium ion with a ___STABLE____________ charge. At the same time, the chlorine atom ___LOSES_________ (gains/loses) one electron to form an ion with a __STABLE 84. ___________ charge.

How can we tell whether an atom will lose or gain electrons to reach a stable structure of 8 electrons in its valence shell? a) In general, an atom with 1, 2, or 3 electrons in its valence shell tends to lose electrons and form a positively charged ion. ) In general, atoms that have 6 or 7 electrons in their valence shells gains electrons and form negatively charged ions. c) In general, atoms with 4 or 5 electrons in their valence shells usually do not form ions.

Ionic Bonds Consider the reaction between sodium and chlorine. Na

+ Cl  Na+ + Cl-

The sodium ion and the chloride ion are oppositely charged. These ions are held together by the attraction of their opposite charges. We say that there is an ionic bond between the sodium and the chloride ion.

An ionic bond is produced whenever one atom loses one or more electrons and another atom gains one or more electrons. 85. In the reaction Zn + S  Zn2+ + S2- , the zinc ion and the sulfur ion are held together by an __IONIC_______ bond. 86. When a sodium atom combines with a chlorine atom according to the equation Na + Cl  Na+ + Cl- , a compound containing a positive...