CHEMISTRY:TOPIC ONE Flashcards
the concept that matter is composed of timy discrete particles is generally attributed to the
greeks
the first subatomic particle discovered was the
electron
according to the law of the conservation of mass, if the products of a reaction have a mass of 64 g, then the total mass of the reactants
must be equal to 64g
the gold foil experiment led scientists to conclude that an atoms
volume is mainly unoccupied
the model of the atom that pictured the atom with electrons stuck randomly throughout the mass of the atom was called
plum pudding model
after bombarding a gold foil sheet with alpha particles, scientists concluded that atoms mainly consist of
empty space
experimental evidence indicated that the nucleus of an atom
contains most of the mass of the atom
daltons atomic theory states that
atoms of a given element must be identical
modern theory pictures an electron as
both a particle and a wave
what are the major differences between the plum pudding and planetary models of the atom
the planetary model contains a nucleus and electrons orbiting
why did rutherford conclude that the atom was mostly empty space
most alpha particles went through it
what is a major difference between the rutherford and the wave mechanical models of the atom
the electrons are in orbitals
the atomic mass of an element is defined as the weighted average mass of that elements
naturally occuring isotopes
element x has two isotopes. If 72% of the element has an isotomic mass of 84.9 amu and 28% has an isotopic mass of 87 amu, the average atomic mass of element x is numerically equal to
(0.720)(84.9) + (0.280)(87)
a neutral atom with 6 electrons and 8 neutrons is an isotope of
carbon
the major portion of an atoms mass consists of
neutrons and protons
atoms of 16O, 17O, and 18O have the same number of
protons but a different number of neutrons
a neutron has approximately the same mass as
a proton
the total number of protons and neutrons in the nuclide 35 over 17 Cl is
35
what si the nuclear charge of an atom with a mass of 23 and an atomic number of 11
11+
compared to the charge and mass of a proton, an electron has
an opposite charge and a smaller mass
when electrons in an excited state fall to lower energy levels, energy is
released
the characteristic bright line spectrum of an atom is produced when
electrons move from higher to lower energy levels
when the electrons of an excited atom fall back to lower energy levels, the emission of energy produces
spectral lines
what particle or particles contribute to the mass number of an atom
protons and neutrons
compare the charge and mass of an electron and a neutron
electron is negative with no mass
neutron is neutral with 1 amu
which atom in the ground state contains one completely filled p orbital
neon
what is the total number of electrons in the second principal energy level of a calcium atom in the ground state
8
what is the total number of occupied s orbital in an atom of nickel in the ground state
4
what is the total number of occupied principal energy levels in a neutral atom of neon in the ground state
2
in an atom of lithium in the ground state, what is the total number of orbitals that contain only one electron
1
what is the total number of completely filled principal energy levels in an atom of argon in the ground state
3
what is the total number of electrons needed to completely fill all the orbitals in an atoms second principal energy level
8
what is the total number of sublevels in the fourth principal energy level
4
what sublevel contains a total of five orbitals
d
what is the maximum number of electrons that can occupy the fourth principal energy level of an atom
32
what is the total number of unpaired electtrons in an atom of exygen in the ground state
2
what is the total number of completely filled sublevels found in an atom of krypton in the ground state
4
Which of the following cannot be decomposed by chemical means
1 sodium
2 ethanol
3 sucrose
4 water
Sodium 
A compound differs from an element in that a compound
Can be decomposed by chemical reaction
A compound differs from a mixture and a compound always has a
Homogenous composition
A pure substance that is composed only of identical atoms is classified as
An element
Most elements are
Metals
What is a characteristic of all mixtures?
Their compositions may vary
Heterogeneous material may be
A mixture
Which of these materials is a mixture, water air, methane, or magnesium?
Air
Each particle contained in hydrogen gas is made up of two identical, hydrogen atoms chemically joined together. hydrogen gas is 
An element
Which of the following materials is a pure substance air water fire or earth
Water
What is an identifying characteristic of a mixture
A mixture can be separated by physical means
Which substance can be decomposed by chemical change, ammonia, aluminum, magnesium, or manganese?
Ammonia
The model of the atom that pictured the atom with electrons traveling in circular orbits, was called the
Planetary model
If 14 g of substance X reacts completely with 16 g of substance Y to form the product XY the mass of XY
Will be 30
Compared to the entire out of the nucleus of the atom is
Smaller and contains most of the atoms mass
In a famous experiment, positively charged particles were aimed at a thin sheet of gold foil, the results of the experiment were that
A few of the particles were repelled showing that the gold has a positive core
Neutral atoms must contain equal numbers of
Protons and electrons
What is true about a compound but not a mixture
The composition of a compound does not vary
Compared with an electron proton has
More mass and an opposite charge
The total number of electrons in a neutral atom of any element is always equal to the atoms
Number of protons
All isotopes of neutral atoms of sodium have
11 protons and 11 electrons
An atom in the excited state contains
More potential energy than an atom in the ground state
As an electron moves from the excited state to the ground, state the potential energy of the electron
Decreases
What particle has the smallest mass?
Electron
An element occurs as a mixture of isotopes. The atomic mass of the element is based upon
Both the masses and the relative abundance of the individual isotopes
100 g of a clear liquid is evaporated in a few grams of the white crystals remain the original liquid
Homogenous mixture
What does different percentages mean? In a word problem?
That it is heterogeneous
Two samples of bronze a uniform material are analyzed and found to contain different percentages of tin. Based on this information bronze is likely a
Heterogeneous mixture
Many companies around the world, manufacture, ammonia what does this mean?
No matter where it is manufactured, it will have the same composition
What is the charge on a particle that contains nine protons 10 neutrons and nine electrons
It’s neutral
An element has two isotopes, 90% of the isotopes have a mass number of 20 amu you while 10% have a mass number of 22 amu you the atomic mass of the element
Is closer to 20amu than to 22amu
If the atomic number of a neutral element is 35 and its nucleus contains 40 neutrons, which is the following correct 1 the atom is bromine and it has 35 electrons in
2 the atom is bromine, and it has a mass number of 40
3the atom is zirconium and it has a mass number of 75.
4 The atom is zirconium and has 40 electrons.
The atom is bromine and it has 35 electrons
An atom of chlorine 35
- Protons 18 neutrons and 17 electrons.
A moon sample was analyzed in a lab. The carbon in the sample was found to be 97.78% carbon 12 and 2.22% carbon 13 according to these data what is the atomic mass of carbon 
12.0222
What model did Ernest Rutherford perform?
Nuclear model
