Neutral atoms contain equal numbers of
protons and electrons
The atomic symbol for beryllium, 9/4/Be, indicates that the atomic number is
4
(bottom left of the element symbol)
The atomic mass of an atom of carbon is12 amu, and the atomic mass of an atom of oxygen is 16 amu. To produce CO2, 32 g of oxygen combine with 12 g of carbon. The ratio of the mass of oxygen in CO2 to the mass of oxygen in CO is
2:1
Rutherford's gold-foil experiment led him to conclude that...
a dense region of positive charge existed somewhere in the atom
According to the law of definite proportions, any two samples of KCI will have...
the same elements in the same proportions by mass
According to the law of conservation of mass, when sodium, hydrogen, and oxygen react to form a compound, the mass of the compound will be...
equal to the sum of the masses of the reactants
An atom of potassium has 19 p+ and 20 n^0. Its mass number is
39
Which of the following is NOT equal to 1.00 mol of carbon-12?
6.0 g of Carbon
Compared with a mole of lead atoms, a mole of iron atoms...
has the same number of atoms
The molar mass of an element is numerically equal to...
the element's average atomic mass
To calculate the number of atoms present in 2.0 mol of an element, you would...
multiply Avogadro's number of atoms per mole by 2.0 mol
The units of molar mass are
g/mol
To determine the mass in grams of an atom of any element, you would...
divide the mass of a mole of the element by Avogadro's number
The average atomic mass of an element is...
the weighted average of all naturally occurring isotopes of the element
The ancient Greek natural philosopher who first proposed the notion of the atom was
Democritus
The atomic mass of Br is 79.9 amu. What is the mass of 2.0 mol of Br?
159.8 g
The least massive particle in an atom is the
electron
Protons are bound together by
strong nuclear forces
How many moles of silver, Ag, are in a 35.65 g sample of Ag? (The molar mass of Ag is 107.9 g/mol)
0.3304 mol
The behavior of cathode rays in a glass tube containing gas at a low pressure led scientists to conclude that the rays are composed of
negative particles
Neutral atoms of the same element can differ in
mass number
Dalton's Atomic Theory helped to explain the law of conservation of mass because it stated that atoms
cannot be created or destroyed
Which of the following statements are true?
Atoms are mostly empty space
Almost all the mass in an atom is in the nucleus
The smallest particle of of an element that retains the chemical properties of that element is a(n)?
Atom
Different atoms of the same element that have different masses are called
isotopes.
The number of protons in the nucleus of an element is called its
atomic #
The total number of protons and neutrons in the nucleus of an isotope is called its
mass #
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 is always a ratio of small whole numbers. This statement is the law of
Law of Multi proportions
Proton (particle) 1 u (mass) +1 (relative charge) in nucleus (location)
Neutron 1 u 0 in nucleus
Electron 1/1800 u -1 orbits nucleus
...
What is molar mass? How is it related to atomic mass?
*Mass in grams of 1 mole of an atom of a pure substance
*Equal to the average atomic mass, but has different # of atoms and label
The atomic number of nickel-60 is 28. How many neutrons does this isotope have?
32
Carbon-14 has 8 neutrons. What is the atomic number of Carbon-14?
14-8=6
A neutral atom of Silicon-30 contains 14 protons. How many electrons does it have?
14+ + 14- = 0 charge
Oxygen has 3 naturally occurring isotopes in the following proportions: oxygen-16, 99.762% (15.99491 amu); oxygen-17, 0.038000% (16.99913 amu); oxygen-18, 0.20000% (17.99916 amu). Calculate the average atomic mass of oxygen.
15.9993001 amu
The average atomic mass of chromium is 52.00 amu. What is the mass of 3.00 mol of chromium?
3.00 x 52.00 = 156 g
How many moles are in a 63.60 g sample of carbon? (The molar mass of carbon is 12.01 g/mol)
5.3 mol
The mass of a sample of nickel (average atomic mass is 58.69 amu) is 11.74 g. How many atoms does it contain?
1.2x10^23
The atomic mass of sulfur is 32.06 amu. How many atoms are present in exactly 2 mol of sulfur?
1.204x10^24 atoms