2016 PISD Chemistry Fall Semester Exam Review KEY

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1 Describe the differences between solids, liquids, and gases. Draw a diagram of atoms in the solid state changing to liquid state changing to gaseous state.

Solids have tightly packed particles, with high density. They have a definite volume and shape. Liquids have particles that move past each other. Their density is lower than solids. They have definite volume but take the shape of their container. Gases have particles that are very far apart from each other. They have a density about 1000 times less than a solid. They take the volume and shape of whatever container they are put in.

2 Explain the difference between an extensive property and an intensive property. Give 4 examples of each.

Extensive properties depend on the amount of matter that you have: mass, volume, length, amount of energy. Intensive properties do not depend on the amount of matter present: density, boiling point, melting point, ability to conduct heat/electricity.

3 Explain the difference between a physical change and a chemical change. Give 4 examples of each.

Physical changes do not change the identity of the substance: cutting paper, dissolving a solid in water, boiling, freezing. Chemical changes result in a new substance being formed: burning charcoal, digesting food, photosynthesis, forming water from hydrogen and oxygen.

4 Explain the difference between a mixture and a pure substance. Give 4 examples of each.

A mixture is a blend of substances that can be physically separated: oil and water; salt and sand; blood; milk. A substance is a form of matter that cannot be broken down without a chemical reaction—it is either an element or a compound: CO2, H2O, copper, gold

5 Explain what apparatus and procedure you would use to separate a mixture of sand, salt, water, and iron shavings.

First, use a magnet to separate the iron from the mixture. Then add the sand and salt mixture to water to dissolve the salt. Pour the mixture through a filter to separate out the sand. Boil the saltwater solution to remove the water and remain with salt.

2016 PISD Chemistry Fall Semester Exam Review KEY

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6 For each scientist in the table below, discuss their experiment, including special equipment, their key conclusion, and how it changed our view of the atom:

Scientist Experiment/Key Equipment Key Conclusions How did it change our view of the atom?

Thomson

Cathode ray tube: every gas had a bright stream of light, which was attracted to a positive plate, cast a shadow, and moved a pinwheel

Every element contains negative particles—electrons, which have mass

Atoms have smaller particles in them; if every element contains negative particles, it must also contain positive charge

Rutherford

Gold Foil Experiment: alpha particles were shot at gold foil. Most passed straight through, but some were deflected back at high angles

Atoms have a small, dense, positive nucleus surrounded by mostly empty space

All of the positive charge in an atom is centered in a tiny fraction of the atom’s volume

Dalton Dalton’s Atomic Theory: -All matter is composed of atoms -Atoms are indivisible and indestructible -All atoms of the same element are identical in mass and properties -Compounds are formed by a combination of two or more different kinds of atoms -A chemical reaction is a rearrangement of atoms

-First evidence-based explanation of the atom -Gave a definition of a compound and of chemical reactions

-Atoms are indivisible because there are protons, neutrons, and electrons -All atoms of the same element are not identical in mass because of isotopes

Bohr Bohr Atomic Model: -The atoms has a small, positively charged nucleus surrounded by electrons that travel in circular orbits, similar to the planets in the solar system -Sometimes called the Shell Model of the Atom

-Gives quantized energy levels for the orbit of electrons, which explains why the electrons do not fall into the nucleus -Explains the behavior or electron energy level transitions for a hydrogen atom model

-Simplistic in its treatment of the electron path as a simple circle, instead of a 3D shape

2016 PISD Chemistry Fall Semester Exam Review KEY

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7 Use the table to determine which two atoms are isotopes of the same element. A & D

8 Solve the following mole calculations: a. How many grams are in 4.23 moles of calcium?

4.23 mol Ca x 40.078 𝑔

𝑚𝑜𝑙 𝐶𝑎 = 170 g Ca

b. How many moles are in 56.98 grams aluminum?

56.98 Al x 1 𝑚𝑜𝑙 𝐴𝑙

26.98 𝑔 𝐴𝑙 = 2.112 mol Al

c. How many atoms are in 13.5 grams of zinc?

13.5 g Zn x 1 𝑚𝑜𝑙

65.39 𝑚𝑜𝑙 x

6.02 𝑥 1023𝑎𝑡𝑜𝑚𝑠

𝑚𝑜𝑙 = 1.24 x 1023 atoms Zn

d. How many moles are in 3.450 x1023 atoms of lead?

3.450 x1023 atoms of Pb 1 𝑚𝑜𝑙𝑒 𝑃𝑏

6.02 𝑥 1023 𝑎𝑡𝑜𝑚𝑠 𝑃𝑏 = 0 .5731 mol Pb

e. How many moles are in 2.45 x 1023 atoms of magnesium?

2.45 x 1023 atoms Mg x 1 𝑚𝑜𝑙𝑒 𝑀𝑔

6.02 𝑥 1023𝑎𝑡𝑜𝑚𝑠 𝑀𝑔 = .407 mol Mg

f. How many grams are in 7.651x1024 atoms of silver?

7.651 x 1021 atoms Ag x 1 𝑚𝑜𝑙 𝐴𝑔

6.02 𝑥 1023𝑎𝑡𝑜𝑚𝑠 𝐴𝑔 x

107.868 𝑔 𝐴𝑔

1 𝑚𝑜𝑙 𝐴𝑔 = 1.37 g Ag

9 Perform the following calculations a. Find the density of a rectangular piece of metal with mass of 48.5 g and the dimensions 2.0cm by 3.0cm by

7.0cm. d = 𝑚

𝑣 =

48.5𝑔

(2𝑥3𝑥7)=42 𝑐𝑚3 = 1.2 g/cm3

b. Find the volume of a substance with density of 1.79 g/mL and mass of 34.5 g.

v = 𝑚

𝑑 =

34.5𝑔

1.79 𝑔/𝑚𝐿 = 19.3 mL

c. Find the mass of a coin with volume of .75 cm3 and density of 2.73 g/cm3. m = d·v = (.75 cm3)(2.73 g/cm3) = 2.05 g

d. A measured mass of an unreactive metal was dropped into a graduated cylinder half filled with water. The following measurements were made. What is the density of the metal?

Mass of metal 27.275 g

Volume of water before addition of metal 11.4 mL

Volume of water after addition of meatal 15.8mL

d = 𝑚

𝑣 =

27.275 𝑔

(15.8−11.4)=4.4 𝑚𝐿 = 6.2 g/mL

e. 12.5 m to cm

12.5 m x 102 𝑐𝑚

1𝑚 =1250 cm

2016 PISD Chemistry Fall Semester Exam Review KEY

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f. 8.7 g to kg

8.7 g x 1𝑘𝑔

102 𝑔 =0.0087 kg

g. 42.0 mL to nL =4.2 x 107 nL

42.0 mL x 1𝐿

103 𝑚𝐿 x

109 𝑛𝐿

1𝐿 =4.20 x 107 nL

h. Convert 5.32 kg to µg

5.32 kg x 103 𝑔

1𝐾𝑔 X

106 𝜇𝑔

1𝑔 = 5.32 x 109 µg

10 Which atoms are isotopes of the same element? a)

11 Define the mole a. How many atoms are in 1 mole of zinc? 6.02 x 1023 atoms of Zn b. How many grams are in 1 mole of zinc? 65.38 g/mole of Zn

12 Sketch out the electromagnetic spectrum. Include: x-rays, microwaves, gamma rays, UV light, IR light, visible light, and radio waves.

a. Show how the frequency of electromagnetic radiation goes from low to high across the spectrum. b. Show how the wavelength of electromagnetic radiation goes from long to short across the spectrum. c. Show how the energy of electromagnetic radiation goes from low to high across the spectrum. high frequency low frequency short wavelength long wavelength high energy low energy

gamma rays X rays UV visible light IR microwaves, radar radio, TV

13 Sketch out the visible light spectrum. Label the colors. a. Show how the frequency of electromagnetic radiation goes from low to high across the spectrum. b. Label 400nm and 700nm. c. Show how the energy of electromagnetic radiation goes from low to high across the spectrum.

high frequency low frequency 400 nm wavelength V I B G Y O R 700 nm wavelength high energy low energy

14 Perform the following calculations: a. What is the frequency of electromagnetic radiation with a wavelength of 1.5 x 10-3 m?

frequency = speed of lightwavelength = 3.00 x 108 m/sec

1.5 𝑥 10−3 𝑚 = 2.0 x 1011 Hz

b. What is the wavelength of electromagnetic radiation with a frequency of 2.8 x 1015 Hz?

wavelength = speed of lightfrequency = 3.00 x 108 m/sec

2.8 𝑥 1015 𝐻𝑧 = 1.1 x 10-7 m

c. What is the energy of electromagnetic radiation with a frequency of 5.9 x 1016 Hz?

energy = Planck's constant x frequency = (6.63 x 10-34 Js)(5.9 x 1016 Hz) = 3.91 x 10-17 J

2016 PISD Chemistry Fall Semester Exam Review KEY

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15 Write the electron configuration and noble gas configuration for the following elements:

a. Phosphorus (atomic #15) 1s22s22p63s23p3 b. Palladium (atomic #46) 1s22s22p63s23p64s23d104p65s24d8 c. Potassium (atomic #19) 1s22s22p63s23p64s1

16 For each of the following groups, what ending electron configuration do the elements have?

a. Group 1 and 2 elements Group 1: s1 Group 2: s2 b. Group 13 to 18 elements all end with p, from p1 (group 13) to p6 (group 18) c. transition metals all end with d, from d1 to d10 d. inner transition metals all end with f, from f1 to f14

17 Explain the contributions of Mendeleev and Mosely to the modern periodic table arrangement. How is the modern periodic table arranged?

Dmitri Mendeleev gets credit as "Father of the Periodic Table." He arranged the elements by mass and reactivity, leaving blank spaces for those he thought were still undiscovered. Moseley later rearranged the table by atomic number (which is how the modern periodic table is arranged).

18 For each of the following families on the periodic table, list how many valence electrons they have and what you know of their properties:

Alkali metal Alkali earth metals Halogens Noble gases

1 valence electron Form ions with +1 charge Fairly reactive as group

2 valence electrons Form ions with +2 charge

7 valence electrons Flourine is most electronegative element Form ions with -1 charge Found as diatomic elements in nature (F2, Br2, Cl2, I2)

8 valence electrons (except He which has 2) Unreactive Do not form compounds

19 Explain the group and period trends on the periodic table for the following

a. atomic radius: group trend--radius increases, because additional energy levels are further from the nucleus periodic trend--radius decreases, because electrons are added at the same energy level and are increasingly attracted to the larger nucleus

b. ionization energy: group trend--energy decreases, because it is easier to remove electrons that are further from the nucleus periodic trend--increases, because it is more difficult to remove the electrons as they are increasingly attracted to the larger nucleus

c. electronegativity: group trend--in general, decreases down a group periodic trend--in general, increases across a period Highest electronegativity: fluorine Lowest electronegativity: cesium.

d. atomic mass: group trend-in general, increases down a group periodic trend—in general, increases across a period

2016 PISD Chemistry Fall Semester Exam Review KEY

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e. ionic radius: cations—are smaller than the atom they came from anions—are larger than the atom they came from

20 Fill out the table below for the different types of bonds:

21 Explain how electrons move in a metallic bond and why they are considered good conductors of heat and electricity, malleable, and ductile.

Metal atoms pack closely together and their outer orbitals overlap. This allows the valence electrons to move freely throughout the lattice. These are known as delocalized electrons. The attraction between the metal cations and the surrounding sea of valence electrons is known as metallic bonding. The free movement of the valence electrons is what allows for electrical conductivity--the electrons move towards a positive charge, and this movement is a current. Because there are no repulsive forces within a metal lattice, any force on the lattice causes its structure to rearrange, rather than break, which accounts for the malleability and ductility of metals.

22 Draw the Lewis valence dot structure for the following atoms a. K b. Cl c. S d. N

Ionic Covalent

Types of elements involved with this type of bonding

metal + nonmetal two or more nonmetals

What holds the atoms together?

ionic forces of attraction between oppositely charged ions

sharing of electrons between two atoms

What properties do these types of compounds have?

crystalline solids brittle high melting points electrolytes called "salts"

can have many physical forms low melting points non-electrolytes

2016 PISD Chemistry Fall Semester Exam Review KEY

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23 Draw the Lewis dot structure for the following compounds. PAP ONLY: identify the molecular and electron pair geometries of each

a. CH4 Tetrahedral

b. H2O tetrahedral- bent

c. PF3 Tetrahdral- trigonal pyramidal

d. CO2 linear

e. BH3 Trigonal planar

C

H H

H H

H

O

H

:

P

H

H

H

O = C = O

B

H

H

H

2016 PISD Chemistry Fall Semester Exam Review KEY

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24 Write the chemical formula for each of the following: a. lead (II) oxide PbO b. lead (IV) sulfide PbS2 c. barium nitrate Ba(NO3)2 d. aluminum hydroxide Al(OH)3 e. zinc chloride ZnCl2 f. copper (II) oxide CuO g. potassium sulfate K2SO4 h. potassium oxide K2O i. cobalt (III) fluoride CoF3 j. copper(II) sulfate pentahydrate CuSO4 ·5H2O k. phosphoric acid H3PO4 l. sulfurous acid H2SO3

25 Name the following compounds:

a. PBr5 phosphorous pentabromide

b. PbI4 lead (IV) iodide c. N2O3 dinitrogen trioxide d. SO3 sulfur trioxide *PAP see below* e. Ag3PO4 silver phosphate f. CaO calcium oxide g. Cu(OH)2 copper (II) hydroxide h. CoCl2·6H2O cobalt(II) chloride hexahydrate i. HCl hydrochloric acid j. NH4Br ammonium bromide

PAP ONLY SECTION: 25d above H2SO4 is sulfuric acid

Isotope Relative Abundance

Mass (amu)

Cu-63 69.17 % 62.929

Cu-65 30.83 % 64.927

26 Using the table above, find the atomic mass of the element.

Average atomic mass = (.6917 x 62.929) + (.3083 x 64.927) = 63.54 amu

27 Determine the number of significant figures in the following measurements a. 20.00 ____4_____ c. 40.080 ___5_____

b. 184,345 __6______ d. 4,000,000 ___1____

28 Perform the following operations and round for appropriate significant figures.

a. (2.324 cm x 1.11 cm) _2.58 cm2________ c. (210.100 g + 235.10 g) __445.20 g_____

b. (8.01 g/3.127 mL) __2.56 g.mL_____ d. (22.1 g + 375.66 g + 5400.132 g) _5797.9 g_____