Quiz 1a (09.11.2020) Flashcards
All nonzero digits are ____
significant
Interior zeros are___
significant
Leading zeroes (zeroes to the left of the first nonzero digit) are ____
not significant
What are the rules about trailing zeros and significant figures?
if there is a decimal point, trailing zeros are significant
What is the multiplication/division rule for significant figures?
the result carries the same number of significant figures as the factor with the fewest significant figures
What is the addition/subtraction rule for significant figures?
the result carries the same number of decimal places as the quantity with the fewest decimal places
Using units as a guide to solving problems is called _______. A unit equation is a statement of two equivalent quantities.
dimensional analysis
A ______ is a fractional quantity of a unit equation with the units we are converting from on the bottom and the units we are converting to on the top.
conversion factor
120 lbs = ___ Kg (There are 0.454 kg in one pound)
54.8 kg
23 miles = ___ ft (There are 5280 feet in one mile)
121,440
451 mL = __ ounces (there are 0.034 ounces in one milliliter)
15.3
What are the three most important laws that led to the development of the atomic theory?
law conservation of mass, law of definite proportions, and law of multiple proportions
Antoine Lavoisier formulated the Law of Conservation of Mass, which states the following:
in a chemical reaction, matter is neither created or destroyed
What is the law of definite proportions?
All samples of a given compound, regardless of their source or how they were prepared have the same proportions of their constituent elements (sometimes called the law of constant composition)
A compound of N and H contains 14g of N for every 3 g of H. What is the mass ratio?
4.7 : 1
What is the law of multiple proportions?
When two elements (call them A and B) form two different compounds, the masses of element B that combine with 1 g of element A can be expressed as a ratio of small whole numbers.
Atoms with the same number of protons but a different number of neutrons are called _____.
isotopes
The relative amount of each different isotope in a naturally occurring sample of a given element is a percentage called the ______ of the isotopes
natural abundance
The sum of the number of neutrons and protons in an atom is its _______.
mass number
How many sig figs are in 23,000
2
How many sig figs are in 4000.00
6
How many sig figs are in 0.00023040?
5
How many sig figs are in 400?
1
Write 0.00333 in scientific notation.
3.33 x 10^-3
Round 0.090035 to 3 sig figs.
0.0900
Round 14,090 to 3 sig figs.
14,100
658.0 + 23.5478 + 1345.29 = ____
Use sig figs
2026.8
23.7 x 3.8 (Use sig figs)
90.
________ is sometimes called atomic weight or standard atomic weight. It represents the average mass of the isotopes that compose that element weighted according to the natural abundance of each isotopes.
atomic mass
The masses of atoms and the percent abundances of isotopes of elements are measured using ________ = a technique that separates particles according to their mass
mass spectrometry
Positive ions are _____.
cations
Negative ions are ____.
anions
What are the properties of metals?
good conductors of heat and electricity, can be pounded into flat sheets (malleability), can be drawn into wires (ductility), shiny, tend to lose electrons
What are the properties of nonmetals?
poor conductors, not ductile, not malleable, they tend to gain electrons
What are the properties of metalloids?
semimetals, have mixed properties, semiconductors because of their immediate (and highly temperature dependent) electrical conductivity
Name the periodic table trends.
Noble gases (8) - mostly unreactive, Alkali metals (1) - all reactive, Alkaline earth metals (2) - fairly reactive, Halogens (7) - very reactive nonmetals
