Chemistry Practice Flashcards (Measurements, Atomic Theory, and Nomenclature)

Flashcards covering SI units, significant figures, errors, atomic theory, isotopes, atomic mass, nomenclature, and basic organic/inorganic chemistry naming.

Scientific measurements are always reported so that the last digit has some uncertainty associated with it. A measurement like 0.12 cm would be reported as __ cm +/- ______ cm.

0.12 cm; 0.005 cm

Convert 1.23 g into kg and micrograms. 1.23 g = kg; µg.

0.00123 kg; 1.23 x 10^6 µg

Trapped zeros are __ in sig figs.

significant

In multiplication and division, the answer has the same number of significant figures as the number with the __ number of significant figures.

smallest

12.1 cm x 1.3745 cm = 16.63145 cm2 = __ cm2.

16.6

In addition and subtraction, the answer has the same number of decimal places as the number with the smallest number of decimal places. 12.2 g + 1.480 g = 13.680 g = _ g

13.7

___ (from counting, a definition or a number of atoms) don’t limit significant figures in calculations.

Exact numbers

1) (4.1 g - 3.6 g) / 1.8 mL? __.

0.28 g/mL

2) 2.3 x 10^-1 g + 3.2 x 10^-2 g? = __ g.

0.262 g

3) 91 seconds in minutes? __.

1.52 minutes

___ refers to how reproducible repeated measurements are.

Precision

___ refers to how close the experimental value is to the true value.

Accuracy

What would high precision, but low accuracy look like?

Measurements close to each other but far from the true value

__ errors result in the experimental value being both too high or too low.

Random

__ errors always cause an experimental value to be either always too high or always too low.

Systematic

Question: what would cause a systematic error in measuring the length of the pencil?

Instrument bias (calibration error)

Illegitimate errors (or human errors) are those that could be avoided such as __ or calculation error.

spillage

A conversion factor lets us change from one unit to another: 1 inch = cm.

2.54 cm

1.8 inches equals cm.

4.57 cm

How long is a 30.0 cm ruler in inches?

11.8 inches

All lab and test calculations must have the correct numbers of significant figures and __.

units

Section Summary includes: __, __, __, and significant figures.

Uncertainty; precision; accuracy

The _ was the first subatomic particle discovered.

electron

As shown by the gold foil experiment, the positive charge and mass must be concentrated in a very small space – the .

nucleus

The gold ___ is 10,000 times smaller than the gold atom.

nucleus

The number of protons an atom has is called its __.

atomic number

___ are atoms of the same element that have different numbers of neutrons.

Isotopes

Thus, an atom consists of a core of protons and neutrons, with electrons orbiting at a great distance. The number of protons an atom has is called its __.

atomic number

The symbol X in X-A-Z notation stands for the element’s .

element symbol

__ is the total number of protons and neutrons in an atom’s nucleus.

Mass number

In isotope notation, A = mass number and Z = atomic number. For example, Zr 90 can be written as Zr-90 or Zr 90. The A represents the number.

mass

1 amu equals g.

1.6605 x 10^-24 g

The masses of all the elements are defined relative to the mass of _.

carbon-12

The isotope carbon-13 explains why carbon’s mass is slightly larger than 12.0000; the isotope is called carbon-___.

13

Chlorine’s atomic mass is the weighted average of its isotopes ³⁵Cl and ³⁷Cl. The weighted average mass is approximately __ amu.

35Cl and 37Cl weighted average ≈ 35.45 amu

For water, H2O we would have: Hydrogen 2 × 1.0079 amu + Oxygen 15.999 amu = amu.

18.0148 amu

1) What is the atomic mass of nitrogen? Isotope data: ¹⁴N 99.63% 14.00 amu; ¹⁵N 0.37% 15.00 amu → atomic mass ≈ amu.

14.01 amu

2) Bromine has two isotopes; One is ⁸¹Br with mass 80.92 amu and abundance 49.31%. The mass of the second isotope is about amu.

78.92 amu

3) Molecular mass of water (H2O) is 2 × 1.0079 amu + 15.999 amu = amu.

18.0148 amu

Molecular mass of CaCl2 is amu.

110.98 amu

Molecular mass of Mg(NO3)2 is amu.

148.33 amu

Molecular compounds are discrete units held together by shared electrons; inorganic ionic compounds are ions held together by opposite charges in crystals. __ compounds contain at least one carbon atom.

Organic

Organic compounds have the general formula indicating exact number and type of atoms; for example CH₄ corresponds to _.

Methane

Hydrocarbons are organic molecules with formula and general form CnH2n+2.

CnH2n+2

Molecular Formula CH₄ is named __; C₂H₆ is __; C₃H₈ is __; C₄H₁₀ is __; C₅H₁₂ is __; C₆H₁₄ is __; C₇H₁₆ is __; C₈H₁₈ is __; C₉H₂₀ is __; C₁₀H₂₂ is __.

Methane; Ethane; Propane; Butane; Pentane; Hexane; Heptane; Octane; Nonane; Decane

2) Naming Inorganic Compounds: If the molecule contains two __ (elements from groups IVA, VA, VIA, VIIA) the elements are listed in group order and the second element ends with -ide. The prefixes mono, di, tri, tetra, penta, hexa indicate the number of atoms.

nonmetals

3) Name the following: a) SO₃ -> __; b) P₄S₁₀ -> __; c) C₃H₈ -> __.

sulfur trioxide; tetraphosphorus decasulfide; propane

Provide the molecular formulas of: a) Phosphorus trichloride -> ; b) Butane -> ; c) Dinitrogen pentoxide -> .

PCl3; C4H10; N2O5

An atom loses electrons to become a ; gains electrons to become an _.

cation; anion

Transition metals have charges in ionic compounds.

variable

In writing ionic formulas, the cation is written first and the overall compound must be electrically neutral; the of cations and anions may be different if charges differ.

charges

Calcium is Ca²⁺ and chloride is Cl⁻; they form the ionic compound .

CaCl2

1) Write the formula for the compound formed when Na⁺ combines with: a) I⁻ -> ; b) N³⁻ -> ; c) CO₃²⁻ -> .

NaI; Na3N; Na2CO3

2) The charge on the sulfite ion in MgSO₃ is __.

2−

Naming Ionic compounds: The cation is always written first; if the metal has multiple charges, include the charge in Roman numerals. Na⁺ → ; Fe²⁺ → ; Fe³⁺ → .

sodium; iron(II); iron(III)

Name the following: a) CaCO₃ -> __; b) CaO -> __; c) NaHCO₃ -> __; d) NH₄I -> __; e) Ni(OH)₂ -> __; f) Zr(SO₄)₂ -> __.

calcium carbonate; calcium oxide; sodium hydrogen carbonate (sodium bicarbonate); ammonium iodide; nickel(II) hydroxide; zirconium(IV) sulfate

Write the formula for the following ionic compounds: a) Potassium carbonate -> ; b) Potassium aluminum sulfate -> ; c) Copper(II) nitrate -> ; d) Iron(II) phosphate -> ; e) Calcium hydroxide -> .

K2CO3; KAl(SO4)2; Cu(NO3)2; Fe3(PO4)2; Ca(OH)2

Ni3(PO4)₂ formula indicates nickel in the oxidation state; the compound is named phosphate.

II; nickel(II) phosphate

Name Ni3(PO4)₂ -> __.

nickel(II) phosphate

C2H6 -> __; C3H8 -> __; C7H16 -> __; C8H18 -> __; C9H20 -> __; C10H22 -> __.

Ethane; Propane; Heptane; Octane; Nonane; Decane

CuSO₄ in naming ionic compounds is called .

copper(II) sulfate

NH₄Cl -> __.

ammonium chloride

Mg(NO₃)₂ -> __.

magnesium nitrate

Al(CN)₃ -> __.

aluminum cyanide

Cr₂O₃ -> __.

chromium(III) oxide

ClO₂ -> __.

chlorine dioxide

Heptane formula -> __.

C7H16

Zr(SO₄)₂ -> __.

zirconium(IV) sulfate