CHEM 121.1

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Mixture
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Components can be separated by physical means.
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Element
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Simplest form of a pure substance, composed of one kind of atom, cannot be broken down into other elements.
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Property
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A characteristic of a substance that allows it to be distinguished from other substances. Can be physical or chemical.
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Physical Property
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Can be measured without changing the identity of composition of the substance. The substance remains the same. Color, shape, odor, density, melting point, boiling point.
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Chemical Property
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Describes the way a substance chages or reacts. The substance does not remain the same- the substance changes when a chemical property is measured.

Examples: Ability to burn (flammability), rust, or decompose/rot.

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Physical Change
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A change in which a substance may change its physical appearance, but not its identity or chemical composition.
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Chemical Change
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A change in which a new substance is formed. The substance loses its identity. It changes its chemical composition and therefore its physical properties change too.
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Length Base Unit
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Meter (m)
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Time Base Unit
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Second (s)
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Mass Base Unit
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Kilograms (kg)
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Temperature Base Unit
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Kelvin (K)
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Amount of Substance Base Unit
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Mole (mol)
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Derived Units
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Units that are combinations of base units.

Examples: Speed (m/s), density (g/mL)

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SI Prefix Mega-
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(M) 1,000,000= 10^6
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SI Prfix Kilo-
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(K)1000= 10^3
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SI Prefix Deci-
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(d) 0.1= 10^-1
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SI Prefix Milli-
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(m) 0.001= 10^/-3
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SI prefix Micro-
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(µ) 0.000001= 10^-6
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SI Prefix Nano-
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(n) 0.000000001= 10^-9
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Uncertainty
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Refers to ANY error in an experimental measurement. All lab measurements have an uncertainty because no measuring device can measure a number to an infinite number of decimal places. When scientists make lab measurements, the last digit is always estimated.
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Rules for Significant Figures
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1. All non-zero digits are significant
2. If a zero is between nonzero digits, it is always significant.
3. If a zero is at the beginning of a number it is never significant.
4. If a zero is at the end of a number and after a decimal point it is always significant.
5. If a zero is at the end of a number with no decimal point you cannot determine the number of significant figures.
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How many significant figures does 5.006 cm have?
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4
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How many significant figures does 3.76 g have?
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3
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How many siginificant figures does 0.0008 cm have?
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1
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How many significant figures does 1.2000 m have?
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5
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How many significant figures does 7.4 x 10^3 g have?
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2
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Convert 6.0 kg to ng
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6.0 x 10^12 ng
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Convert 7420 seconds to days.
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8.59 x 10-2 days
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Convert 5 Mg to µg
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5 x 10^12 µg
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Describe the nucleus of an atom.
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Central particle, small with high mass and density, made up of protons (+ charge) and neutrons (no charge), and does not take part in chemical reactions.
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Describe the eletrons in an atom.
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The smallest part of an atom, moves outside around the nucleus, carries a negative charge, takes part in chemical reactions.
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1 nm = nanometer = 1 x 10^-9 m
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What does the atomic number stand for?
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The atomic number (Z) represents the number of protons in the nucleus.
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What does the mass number represent?
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The mass number (A) represents the sum of protons and neutrons in the nucleus.
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Define Isotope
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Atoms of the same element having differet masses due to different numbers of neutrons in the nucleus.
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What are the 3 hydrogen isotopes and their chemical make-up?
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1. Protium- contains one proton and one electron.

2. Deuterium- contains one proton, one neutron, and one electron.

3. Tritium- contains one proton, two neutrons, and one electron.

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What is the formula for isotopic notation?
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AZX

 

Where “A” represents the mass number, “Z” represents the atomic number, and “X” is the chemical symbol.

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How do you calculate the average atomic mass of a set of isotopes?
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To find the average atomic mass of a set of isotopes, multiply the mass of each isotope by its % abundance (converted to a decimal) and then add up all of the results.
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What information does each block of the periodic table contain?
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Atomic number, chemical symbol, and atomic weight.
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What information does each block of the periodic table contain?
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Atomic number, chemical symbol, and atomic weight.
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What are periods?
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Rows of the periodic table. Atomic numbers increase by 1 with each succeding element.
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What are groups/ families?
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Groups are numbered in 2 ways. The new method uses numbers 1-18, the older method uses numbers with letters, 1A…
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What is a molecular formula?
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Shows the kinds of atoms and exact number of atoms present in a compound.
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What is an empirical formula?
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Shows the smallest whole number ratio of atoms in a compound.
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Write this molecular formula in empirical form.

 

C6H12O6

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CH2O
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Write this molecular formula in empirical form.

 

C2H4

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CH2
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Write this molecular formula in empirical form.

 

P4O10

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P2O5
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What are the rules for naming Binary Molecular Compounds?
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1. Name of the element farthest to the left in the periodic chart is written first.

2. If both elements are in the same group, the lower element is written first.

3. The second element must have an -ide ending.

3. Greek prefixes give the numbers of each element.

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Mono-
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1
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Di-
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2
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Tri-
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3
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Tetra-
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4
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Penta-
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5
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Hexa-
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6
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Hepta-
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7
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Octa-
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8
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Nona-
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9
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Deca-
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10
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Name this molecular compound.

 

NO

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Nitrogen Monoxide
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Name this molecular compound.

 

N2O4

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Dinitrogen Tetroxide
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Name this molecular compound.

 

SO2

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Sulfur Dioxide
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Define Ion
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An atom that has a positive or negative charge.
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Define Cation
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A positive ion. The atom must lose electrons for a cation to form.
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Define Anion
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A negative ion. An atom must gain electrons to form an anion.
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Why do atoms form ions?
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Atoms must gain or lose electrons in order to aquire the same number of electrons as a noble gas.

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