Chapter 2

The first person to describe an element as being composed of identical atoms was _____. a. J.J. Thomson b. John Dalton c. Dmitri Mendeleev d. Niels Bohr

b. John Dalton pg. 28: according to Dalton, an element was composed of identical atoms that reacted the same way chemically.

What are the fundamental particles of an atom? a. quark, positron, negatron b. nucleon, electron, proton c. proton, neutron, quark d. proton, electron, neutron

d. proton, electron, neutron pg. 29: the fundamental particles of an atom are the electron, proton, and the neutron.

A positively charged nucleus surrounded by negatively charged electrons in well-defined orbits is the _____ model of the atom. A) Bohr B) Thomson C) Rutherford D) Dalton

A) Bohr Pg. 29: Bohr improved upon Rutherford's description of the atom. Simply put, the Bohr atom contains a small, dense, positively charged nucleus surrounded by negatively charged electrons that revolve in fixed, well-defined orbits about the nucleus.

An atom that loses or gains one or more electrons is a(n)_____. A) ion B) molecule C) isotope D) isomer

A) ion Pg. 31

The innermost electron shell is symbolized by the letter _____. A) J B) K C) L D) M

B) K Pg. 32: see table 2-2 K = 1, L = 2, M = 3, N = 4, O = 5, P = 6, Q = 7

Rutherford's experiments in 1911 showed that the atom was composed of _____. A) electrons with well-defined orbits B) a nucleus with an electron cloud C) electrified plum pudding D) a ball of hooks and eyes

B) a nucleus with an electron cloud Pg. 29: Ernest Rutherford in 1911 disproved Thomson's model of the atom. Rutherford introduced the nuclear model, which described the atom as containing a small, dense, positively charged center surrounded by a negative cloud of electrons. He called the center of the atom the nucleus.

The shell number of an atom is called the _____. A) alpha particle B) chemical element C) principal quantum number D) half-life number

C) principal quantum number Pg. 32: physicists call the shell number n the principal quantum number

Aluminum has an atomic number of 13. How many protons does it have? a. 13 b. 26 c. 27 d. none of the

a. 13 Pg. 34: the number of protons is called the atomic number, represented by "Z"

During beta emission, an atom releases _____. Select one: a. electrons b. positrons c. protons d. neutrons

a. electrons pg. 37: during beta emission, an electron created in the nucleus is ejected from the nucleus with considerable kinetic energy and escapees from the atom.

The chemical element is determined by the number of _____ in the atom. a. protons b. electrons c. neutrons d. nucleons

a. protons pg. 30: the number of protons determines the chemical element.

The maximum number of electrons that can exist in an electron shell is calculated with the formula _____. Select one: a. 2n b. 2n^2 c. 2/n d. 2/n2

b. 2n^2 pg. 32: maximum number of electrons er shell = 2n^2, where n is the shell number K = 1, L = 2, M = 3, N = 4, O = 5, P = 6, Q = 7

Two identical atoms which exist at different energy states are called _____. a. isotopes b. isomers c. isotones d. isobars

b. isomers pg. 36: isomers are identical atoms except that they exist indifferent energy states because of differences in nucleon arrangement.

A chemical compound is any quantity of _____. a. one type of atom b. one type of molecule c. two types of molecules d. two or more types of atoms

b. one type of molecule Pg. 36: The smallest particle of an element is an atom. The smallest particle of a compound is a molecule. Atoms of various elements may combine to form molecules. A chemical compound is any quantity of one type of molecule.

An atom in a normal state has an electrical charge of _____. a. one b. zero c. positive d. negative

b. zero pg. 31: in their normal state atoms are electrically neutral; the electric charge on the atom is zero.

The term "atom" was first used by the _____. a. Ethiopians b. British c. Greeks d. Romans

c. Greeks pg. 27: the Greeks used the term atom, meaning "indivisible" [ a (not) + temon (cut) ] to describe the smallest part of the four substances of matter.

The periodic table of the elements was developed by _____ in the late 19th century. a. Bohr b. Rutherford c. Mendeleev d. Roentgen

c. Mendeleev pg. 28: Dmitri Mendeleev showed if the elements were arranged in order of increasing atomic mass, a periodic repetition of similar chemical properties occurred. Mendeleev's work resulted in the first periodic table of the elements.

The atomic number of an element is symbolized by the letter _____. a. A b. X c. Z d. n

c. Z Pg. 34: the number of protons is called the atomic number, represented by "Z"

When atoms of various elements combine, they form _____. a. isotopes b. compounds c. molecules d. ions

c. molecules pg. 36: atoms of various elements may combine to form structures called molecules.

The only difference between x-rays and gamma rays is their _____. a. energy b. size c. origin d. name

c. origin PG. 42: the only difference between x-rays and gamma rays is their origin. Gamma rays are emitted from the nucleus of a radioisotope and are usually associated with alpha or beta emission. X-rays are produced outside the nucleus in the electron shells.

The binding energies, or energy levels, of electrons are represented by their _____. Select one: a. atomic numbers b. atomic mass units c. shells d. isotopes

c. shells pg. 31: Electrons can exists only in certain, which represent different electron binding energies.

The atomic number of molybdenum is 42 and the atomic mass number is 98. How many neutrons does it have? a. 42 b. 98 c. 21 d. 56

d. 56 Pg. 34: the number of protons plus the number of neutrons in the nucleus of an atom is called the atomic mass number ("A") atomic mass - atomic number = neutrons

The _____ is the least penetrating form of ionizing radiation. a. beta particle b. x-ray c. gamma ray d. alpha particle

d. alpha particle pg. 41: the energy of an alpha particle is quickly lost. It has a very short range in matter. Consequently, alpha radiation from an external source is nearly harmless because the radiation energy is deposited in the superficial layers of the skin.

The smallest particle that has all the properties of an element is a(n) _____. a. neutron b. proton c. electron d. atom

d. atom pg. 27: the atom is the smallest particle of matter that has the properties of an element.

When an atom has the same number of protons as another, but a different number of neutrons, it is called an _____. a. isomer b. isobar c. isotone d. isotope

d. isotope pg. 35: isotopes of a given element contain the same number of protons, but varying numbers of neutrons.

A neutral atom has the same number of _____ and electrons. a. quarks b. neutrinos c. neutrons d. protons

d. protons pg. 31: in their normal state atoms are electrically neutral; the electric charge on the atom is zero.