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Chapter 3 Chem. Test (Westfall)

Terms in this set (32)

The behavior of cathode rays in a glass tube containing gas at low pressure led scientist to conclude that the rays were composed of _____________________
c. negative particles
The basic principles of atomic theory that are still recognized today were first conceived by ______________________
c. Dalton
An example of the law of multiple proportions is the existence of _____________________
c. CO and CO2
Atoms of the same element can differ in _____________________
b. mass number
Dalton's atomic theory helped to explain the law of conservation of mass because it stated that atoms _____________________
d. could not be created or destroyed
Milliken's experiments determined _____________________
c. the approximate value of the electron's mass
In Rutherford's experiment, a small percentage of the positively charged particles bombarding the metal's surface _____________________
b. were deflected back toward the source from the metal
Most of the volume of an atom is made up of the _____________________
c. electron cloud
If a particular compound is composed of elements A and B, the ratio of the mass of B to the mass of A will always be the same. This is a statement of the law of _____________________
definite proportions
The amount of a substance that contains a number of particles equal to the number of atoms in exactly 12 g of carbon-12 is referred to as a(n) _____________________
mole
Since any metal cathode used in a cathode-ray tube produced the same charged particles, it was concluded that all atoms contain _____________________
electrons
The smallest particle of an element that retains the chemical properties of that element is a(n) _____________________
atom
Atoms of one element that have different masses are called _____________________
isotopes
the total number of protons and neutrons in the nucleus of an isotope is called its _____________________ number.
mass
The short-range attractive forces that hold the nuclear particles together called _____________________
nuclear forces
The number of protons in the nucleus of an element is called its _____________________ number.
atomic
If two or more compounds are composed of elements A and B, the ratio of the masses of B combined with 1 g of A make each compound a ratio of small whole numbers. This is the statement of the law of _____________________
multiple proportions
Dalton's atomic theory agreed with the modern atomic theory EXCEPT for the statement that all atoms of the same element have the same _____________________
mass
Proton: Mass number / Relative charge / Location
1; 1+; in the nucleus
Neutron: Mass number / Relative charge / Location
1; 0; in the nucleus
Electron: Mass number / Relative charge / Location
0; 1-; outside the nucleus (in the electron cloud)
Give three of the main concepts in Dalton's atomic theory.
(1) All matter is composed of extremely small particles called atoms. (2) All atoms of an element are identical in size, mass, and other properties; atoms of different elements differ in size, mass and other properties.
(3) Atoms cannot be subdivided, created, or destroyed. (4) Atoms of different elements combine in simple whole-number ratios to form chemical compounds. (5) In chemical reactions, atoms are combines, separated, or rearranged.
What is molar mass? How is it related to atomic mass?
Molar mass is the mass of a given substance divided by the amount of that substance, measured in g/mol. contains 6.022137 x 10^23 particles, or Avogadro's number of particles. The atomic mass is the mass of one atom.
Explain why the atomic mass of a particular isotope of an element differs from the average atomic mass of that element.
The atomic mass of a single isotope of an element is its relative mass compared to the mass of carbon-12. The average atomic mass of an element is the weighted average of the masses of all naturally occurring isotopes of an element.
The atomic mass of sulfur is 32.06 amu. How many atoms are present in exactly 2 mol sulfur?
1.204 x 10^24 atoms
How many moles are in a sample of 63.658 g of carbon? (The molar mass of carbon is 12.02 g/mol.)
5.300 mol
The atomic number of nickel-60 is 28. How many neutrons does this isotope have?
32
An atom of silicon-30 contains 14 protons. How many electrons does it have?
14
The mass of a sample of nickel (average atomic mass 58.69 amu) is 11.74 g. How many atoms does it contain?
1.205 x 10^23 atoms
Carbon-14 has 8 neutrons. What is the atomic number of carbon-14
6
Oxygen has three naturally occurring isotopes in the following proportions: oxygen-16, 99.762% (15.994 91 amu); oxygen-17, 0.038000% (16.999 13 amu); oxygen-18, 0.20000% (17.999 16 amu). What is the average atomic mass of oxygen?
15.999 amu
The average atomic mass of chromium is 52.00 amu. What is the mass of 3.00 mol of chromium?
156 g
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