chemistry test review

Place the descriptions of the model of the atom in order of historical progression, from most distant to most recent.

1. Atoms are solid and indivisible 2. Atoms are positive with embedded negative particles 3. Atoms are largely empty space with a positive nucleus and orbiting electrons 4. Atoms have a nucleus with protons that is surrounded by electrons traveling in specific pathways 5. Atoms have a nucleus with protons and neutrons. The nucleus is surrounded by electrons traveling in specific pathways

Place the following atomic scientists in chronological order of their contributions to atomic theory, from most distant to most recent.

1. John Dalton 2. J.J. Thomson 3. Ernest Rutherford 4. Neils Bohr 5. James Chadwick

state two principles from Dalton's atomic theory that have been revised as new information has become available

1. atoms can't be subdivided, created, or destroyed. 2. a given element can have atoms with different masses

Place the models of the atom in order of historical progression, from most distant to most recent.

1. billard ball 2. plum pudding 3. nuclear 4. planetary

How did the outcome of Rutherford's gold foil experiment indicate the existence of a nucleus?

A small amount of alpha particles bounced back instead of going straight through, thus theorizing the atom was not all empty space. A small, dense nucleus lies in the center.

The formation of water according to the equation 2H2 O2 → 2H2Oshows that 2 molecules (made of 4 atoms) of hydrogen and 1 molecule (made of 2 atoms) of oxygen produce 2 molecules of water. The total mass of the product, water, is equal to the sum of the masses of each of the reactants, hydrogen and oxygen. What parts of Dalton's atomic theory are illustrated by this reaction? What law does this reaction illustrate?

Atoms cannot be subdivided, created, or destroyed. Also, atoms of different elements combine in simple, whole-number ratios to form compounds. The reaction also illustrates the law of conservation of mass

Why is Democritus's view of matter considered only an idea, while Dalton's view is considered a theory?

Democritus's view couldn't be supported by experimental evidence while Dalton's could be tested by experiment.

In 1911, Ernest Rutherford conducted his now famous gold foil experiment, During the experiment, alpha particles bombarded a thin piece of gold foil. The alpha particles were expected to pass easily through the gold foil. Every now and then, however, an alpha particle bounced back-an unexpected result. Rutherford concluded that these particles were striking a. A tiny region of positive charge b. a dense region of negative charge c. a dense region of neutrons d. a tiny region with a strong magnetic field

a

Isotopes are atoms of the same element that have different a. masses b. charges c. number of electrons d. atomic numbers

a

To take a weighted average of all the naturally occurring isotopes of an element in order to arrive at an average atomic mass, you would a. multiply the mass of each isotope by the decimal fraction representing its abundance naturally, then add all these products together b. use the isotope with the largest mass c. use the isotope with the most average mass d. add all the masses of all the isotopes, then divide by the number of isotopes

a

4 He 2

alpha particle

the smallest unit of an element that can exist either alone or in molecules containing the same or different elements is the

atom

Experiments with cathode rays being deflected by a magnetic field show that cathode rays are composed of particles that are a. magnetic b. negatively charged c. positively charged d. neutral in charge

b

In 1808, John Dalton established his atomic theory. Which of the following is not part of Dalton's atomic theory a. All matter is composed of atoms b. An atom consists of a nucleus and a cloud of electrons c. Atoms cannot be subdivided, created, or destroyed d. In chemical reactions, atoms are combined, separated, or rearranged

b

John Dalton thought that atoms a. contain molecules b. cannot be broken down further c. are all composed of carbon d. have no mass

b

One mole is defined as a. the volume of a substance with a mass of 12 g b. the amount of a substance that contains as many particles as there are atoms in exactly 12 g of carbon-12 c. the amount of a substance that contains as many particles as there are atoms in exactly 12 g of silver d. an amount of a substance that contains enough atoms to have a mass of 12 g

b

The isotope uranium-235 has 92 protons and 143 neutrons. Therefore, its mass number is a. 92 b. 235 c. 143 d. impossible to determine

b

The total volume of the nucleus of an atom is a. very large compared with the rest of the atom b. Very small compared with the rest of the atom c. about the same size as an electron d. smaller than a neutron

b

We know that objects with like electric charge repel one another. Which statement best explains why protons can remain close to one another in a nucleus a. there is no electric charge in the nucleus of an atom b. A short range force, called the strong nuclear force, binds protons together c. protons are balanced electrically by electrons d. neutrons cancel out the electric force

b

Which is one way that Dalton's atomic theory has been shown to be incorrect a. Atoms can change identity in chemical reactions b. Atoms can be split into subatomic particles c. Atoms can be destroyed by chemical reactions d. Some atoms of a particular element are identical to atoms of other element

b

0 e -1

beta

Except for in the simplest type of hydrogen atom, all nuclei consist of a. protons and electrons b. neutrons and positrons c. protons and neutrons d. electrons and positrons

c

Hydrogen that is composed of atoms with two neutrons is called a. protium b. deuterium c. tritium d. helium

c

Most of an atom is a. dense b. fluid c. empty d. the nucleus

c

Rutherford called the region that deflected alpha particles a. an electron b. a positron c. a nucleus d. a quark

c

The atomic number of an element is a. the mass of the element b. 1 mol of the element c. the number of protons in each atom of the element d. the number of neutrons in each atoms of the element

c

Using improved chemistry equipment in the late 1700s, chemists observed that mass in neither created nor destroyed in a chemical reaction. This scientific law is called the law of a. definite proportions b. gravity c. conservation of mass d. conservation of momentum

c

What is the charge of a neutron a. positive b. negative c. neutral d. none of the above

c

What is the definition of one atomic mass unit a. 1 g of any element b. 1 mol of any element c. 1/2 of the mass of a carbon-12 atom d. 1/12 of the mass of any atom

c

Which of the following statements of Dalton's atomic theory describes conservation of mass a. All matter is composed of atoms b. Atoms of a given element are identical in size, mass, and other properties c. Atoms cannot be subdivided, created, or destroyed d. Atoms of different chemical elements combine in simple whole number ratios to form chemical compounds

c

In cathode-ray tubes, the cathode ray is emitted from the negative electrode, which is called the

cathode

Cathode rays are composed of particles that are now known as a. positrons b. neutrons c. protons d. electrons

d

Electrons can be found a. inside protons b. inside neutrons c. attached to the nucleus d. moving rapidly outside the nucleus

d

If two or more compounds are composed of the same two elements, then the ratio of the masses of the second element that is combined with a certain mass of the first element is always a ratio of small whole numbers. This statement is called the law of a. definite proportions b. conservation of mass c. atomic theory d. multiple proportions

d

Mass number is a. the average atomic mass of an element b. the total number of electrons in an atom of an element c. the total number of protons in an atom of an element d. the total number of protons and neutrons in an atom of an element

d

The fact that every sample of a particular chemical compound contains the same elements in exactly the same proportions by mass is known as the law of a. conservation of energy b. conservation of mass c. atomic theory d. definite proportions

d

Which of the following statements of Dalton's atomic theory describes the law of multiple proportions a. All matter is composed of atoms b. Atoms of a given element are identical in size, mass, and other properties c. Atoms cannot be subdivided, created, or destroyed d. Atoms of different chemical elements combine in simple whole number ratios to form chemical compounds

d

where is the electron located

electron cloud

the subatomic particles that are least massive and most massive, respectively, are the ------ and -------

electrons and nuetrons

According to the quantum theory of an atom, the electron's position in an orbital is known precisely.

false

After measuring the ratio of the charge of a cathode-ray particle to its mass, Thomson concluded that the particles had very large mass.

false

Albert Einstein discovered the neutron.

false

Bohr's planetary model of the atom was the first model to include electrons.

false

Dalton worked with the behavior of liquids as he arrived at his conclusion about atomic theory.

false

Democritus first disproved Dalton's atomic model.

false

Experiments with cathode rays led to the discovery of the neutron.

false

In Rutherford's experiments, alpha particles were used to bombard a very thin sheet of aluminum foil.

false

J.J. Thomson discovered the existence of protons.

false

John Dalton was the first person recorded as thinking that matter was ultimately composed of small particles he named "atomos."

false

Millikan's work led to a new model of the atom.

false

The Law of Conservation of Mass states that all atoms of an element have the same mass.

false

The Rutherford experiment proved the Thomson "plum-pudding" model of the atom to be essentially correct.

false

The first scientist to show that atoms contain any negative particles was John Dalton.

false

The major accomplish of Rutherford's work was to prove the existence of the electrons.

false

Thomson's plum pudding model of the atom was the first one to include a nucleus.

false

y

gamma

Give an example of a chemical or physical process that illustrated the law of conservation of mass

ice to water. ice cubes will have the same mass once they melt into water

explain the difference between the mass number and the atomic number of a nuclide

mass number is the total number of protons and neutrons in the nucleus of an isotopes. Atomic number is the total number of protons in the nucleus of each atom of an element

how do you calculate average atomic mass

multuply the mass by the percent abundance of each isotope and then add together

Is an atom positively charged, negatively charged, or neutral?

neutral

1 n 0

neutron

a nuclear particle that has no electrical charge is a

nuetron

A cathode ray produced in a gas-filled tube is deflected by a magnetic field. A wire carrying an electric current can be pulled by a magnetic field. A cathode ray is deflected away from a negatively charged object. What property of the cathode ray is shown by these phenomena?

particles are negatively charged

0 e 1

positron

1 p 1

proton

a positively charged particle found in the nucleus is called a

proton

The element boron, B, has an atomic mass of 10.81 amu according to the periodic table. However, no single atom of boron has a mass of exactly 10.81 amu. How can you explain this difference?

the atomic mass of 10.81 amu is a weighted average atomic mass of the isotope.

According to Bohr, electrons cannot reside at point C in the figure below.

true

According to the Bohr model of the atom, the single electron of a hydrogen atom circles the nucleus in specific allowed orbits.

true

DeBroglie, Planck, Heisenberg, and Einstein helped to determine the quantum theory of the atom.

true

If the Thomson model of the atom had been correct, Rutherford would have observed alpha particles going through the gold foil with little or no deflection.

true

In Bohr's atomic theory, when an electron moves from one energy level to another energy level more distant from the nucleus, energy is absorbed.

true

In determining his model of the atom, Bohr worked with hydrogen's line emission spectrum.

true

In modern atomic theory, most of the volume of an atom is occupied by the electrons.

true

In oxides of nitrogen, such as N2O, NO, NO2, and N2O3, atoms combine in small whole-number ratios. This evidence supports the law of multiple proportions.

true

John Dalton formalized an atomic theory that gained acceptance in the early 19th century.

true

Modern atomic theory includes the idea that the nucleus of an atom is a very small, dense region that contains the large majority of the atom's mass.

true

One premise of Dalton's atomic theory stated that atoms cannot be divided. This premise has been modified as atomic theory has progressed over time.

true

The alpha-particle scattering experiment led to the conclusion that the nucleus of an atom contains a dense center of positive charge.

true

The discovery of the neutron involved bombarding atoms of beryllium with alpha particles.

true

The gold foil experiment showed that large regions of atoms consisted of empty space.

true

The key difference between the models of the atom proposed by Bohr and Rutherford is that Bohr's model has the electrons moving in fixed energy levels, while in Rutherford's they do not.

true

The work of Curie, Geiger, Bequerel, and Rontgen dealt with radioactivity.

true