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78 terms


Mass, indivisible.
Dalton incorporated the law of conservation of _____ into his atomic theory by asserting that atoms are _____.
If each atom of element D has 3 masses and each atom of element E has 5
mass units, a molecule composed of one atom each of D and E has _____ mass units.
Multiple Proportions
In oxides of nitrogen atoms combine in small whole-number ratios. This evidence supports the law of _____
The Law of Multiple Proportions
states that two or more compounds different compounds of the same two elements, then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers
equal to
According to the law of conservation of mass, when sodium, hydrogen, and
oxygen react to form a compound, the mass of the compound is
________ (equal to, greater than) the sum of the masses of the
individual element.
John Dalton
Who conceived the principles of the atomic theory?
identical, mass
According to Dalton's atomic theory, atoms of each element are __________ in size, _____ and other properties.
Atoms of the same element may have _____ masses according to modern atomic theory.
Atoms can be subdivided
Which concept of Dalton's atomic theory has been changed?
A negatively charged electrode
What is a cathode?
If an electrical current passes through a glass tube, it causes the surface of
the tube directly across from the cathode to glow. The reason is because the particles of the bean were _______ charged.
Experiments with cathode rays led to the discovery of
Thompson, small
After measuring the ratio of the charge of a cathode-ray particle to its mass, _______ concluded that the particles had a very ________ mass.
negatively charged electrons
Because any element used in the cathode produced _______scientists concluded that all atoms contained electrons.
Rutherford, gold, through, empty, densely, positive
_______ experiments identified the nucleus of that atom. In his experiments, alpha particles were used to bombard thin ______ foil. Most of the particles passed _______ the foil. Because most of the particles passed through, Rutherford concluded that atoms were mostly _______ space. Because a few alpha particles bounced back from the foil, he concluded that they were repelled by _______packed regions of _______ charge.
neutron, mass, positive
A _______has the same _______as a proton, but with no _______ charge.
positively charged, contains all the mass of the atom, densely packed
What are the characteristics of the nucleus of an atom?
protons, electrons, equal
An atom is electrically neutral because the numbers of _________ and _________ are _________
Electron cloud
Most of the volume of an atom is occupied by the _________.
atoms, masses
Isotopes are _________ of the same element that have different _________.
The most common form of hydrogen has no _________.
The atomic number of oxygen, 8, indicates that there are 8
_________ in the nucleus of the an oxygen's atom.
An aluminum isotope consists of 13 protons, 13 electrons, and 14
neutrons. It has a mass number of _________.
The number of atoms in 1 mol of carbon is _________
The atomic number of neon is 10. The atomic number of calcium is 20.
Compared with a mole of neon, a mole of calcium contains an
________ number of atoms.
What is the mass of 1 mol of chromium
atoms of the same element that have different masses
Atoms of different elements have different numbers of ______.
Positively charged sub-atomic particle
Negatively charged sub-atomic particle
Sub-atomic particle with no charge.
Atomic Number
The number of protons found in each atom of an element is known as that element's ______.
Mass Number
Total number of protons and neutrons that make up the nucleus of an isotope.
17 protons, 17 electrons, 20 neutrons
How many protons, electrons, and neutrons are there in Chlorine(Cl) -37? (In that order)
6 protons, 6 electrons, 6 neutrons
How many protons, electrons, and neutrons are there in Carbon(C) -12? (In that order)
24 protons, 24 electrons, 34 neutrons
How many protons, electrons, and neutrons are there in Chromium(Cr) -58? (In that order)
By their mass, (due to) the number of neutrons
How can you tell isotopes apart?
Mass Number
What does the number next to isotopes signify? (Ex. Nitrogen-15)
The central part of an atom containing the protons and neutrons.
Atomic Mass
The average mass of the atoms in an element.
3.00 mol NH3 to grams of NH3
8.00g NaOH to molecules of NaOH
9.02 mol H2O to molecules of H2O
0.2000 mol SO3 to grams of SO3
0.0577 mol
5.657g H2SO4 to moles of H2SO4
earth, water
The ancient Greeks believed that matter is made up of four basic elements: _____, air, fire, and ______.
John Dalton
man who proposed the modern atomic theory.
constant composition
definite proportions.
Either is acceptable, mark as correct.
The law of ________ says that the composition of a compound is always the same.
In science, a prediction is known as a ________.
Electrons, J. J. Thompson
________, tiny, negatively charge particles were discovered by ________.
The number of protons in an atom is always equal to the number of ________.
isotopes differ from one another in their________.
Gold foil experiment
Discovered the nucleus
Electron Cloud
The largest portion of an atom is taken up by the ________.
Symbol for the atomic mass unit is ___.
10, 20, 10
Give the atomic number, mass number, number of electrons
238, 92, 92
Atomic Number = 92
Number of neutrons = 146
Give the mass number, number of protons, number of electrons
13, 27, 13
Number of neutrons = 14
Number of electrons = 13
Give the atomic number, mass number, number of protons
400 B.C. ________ though matter could not be divided indefinitely.
Dalton: All matter is made of ________.
John Dalton
His ideas account for the law of conservation of mass, and the law of constant composition.
Cathode Rays
Materials, when rubbed, can develop a charge difference. This electricity is known as ________when passed through an evacuated tube.
John Dalton
"Billiard Ball" Model
-Atoms are solid and indivisible
"Plum Pudding" Model
-Negative electrons in a positive framework
His model states that atoms are mostly empty space. Negative electrons orbit a positive nucleus.
Shot alpha particles at gold foil. most particles passed through, showing that atoms are mostly empty space.
Thus, this scientist could conclude that the nucleus holds most of the atom's mass.
Scientist who believed:
-Electrons orbit the nucleus in "shells"
-Electrons can be bumped up to a higher shell if hit by another electron or a photon of light.
electrons, atomic (number)
#protons = # of ________ = ________ number
# of ________ = mass number - atomic number
Radioactivity is caused by a large gap between ________ and protons.
(As in Uranium(U) 92p+ 92e- 146n)
Nuclear Forces
Short-range neutron-neutron, proton-proton, and neutron-proton forces that hold nuclear particles together are called ________.
There are no example problems here because I didn't do the practice worksheets and don't have the correct answers.
(answer: type OK)
Oil Drop Experiment. Found the charge of an electron.
divisible, masses
What was incorrect about Dalton's theory:
-Atoms are ________ into smaller particles.
-A given element can have atoms with different ________.
Law of conservation of mass
atoms are neither created nor destroyed.(Law)
Law of constant composition
Law of definite proportions.
Either is acceptable, mark as correct.
elements combine in fixed ratios.(Law)
Law of multiple proportions
If two elements form more than one compound between them, then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers. (Law)