Physical Science Test 2 (Chemistry)

Each vertical column in the periodic table is called a ________

"group."

Each horizontal row in the periodic table is called a _______

"period."

1) How many neutrons are in an atom of Iodine-123? 2) How many protons are in an atom of Potassium-42? 3) What is the mass number of Cobalt, if Co has 32 neutrons?

1) 70 2) 19 3) 27

Consider a radioactive sample with a half-life of one week. How much of the original sample will be left at the end of the fourth week?

1/16 Week 1: ½ Week 2: ½ x ½ = ¼ Week 3: ½ x ½ x ½ = 1/8 Week 4: ½ x ½ x ½ x ½ = 1/16

Which is larger: a lithium atom or a fluorine atom?

A Lithium atom

Element

A material made of only one kind of atom. Pure gold is an example as it is made of only gold atoms.

Compound:

A substance consisting of atoms of different elements. Compounds have properties uniquely different from the elements from which they are made.

Which of these is the nucleus of the helium atom? A. Alpha particle. B. Beta particle. C. Gamma ray. D. All are different forms of helium.

A. Alpha particle. A beta particle is a high-speed electron; a gamma ray is electromagnetic radiation.

Which of these photons has the smallest energy? A. Infrared. B. Visible. C. Ultraviolet. D. All have the same.

A. Infrared In accord with E , the lowest frequency radiation has the smallest energy per photon.

The hydrogen spectrum consists of many spectral lines. How can this simple element have so many lines? A. One electron can be boosted to many different energy levels. B. The electron can move at a variety of speeds. C. The electron can vibrate at a variety of frequencies. D. Many standing electron waves can fit in the shell of the hydrogen atom.

A. One electron can be boosted to many different energy levels.

Which has less energy per photon? A. Red light. B. Green light. C. Blue light. D. All have the same.

A. Red light.

The frequencies of light emitted by an atom often add up to A. a higher frequency of light emitted by the same atom. B. a lower frequency of light emitted by the same atom. C. both of the above. D. none of the above.

A. a higher frequency of light emitted by the same atom. This follows from two energy transitions in an atom summing to equal another energy transition. See the next slide.

Melting a piece of solid gold would be... A. a physical change. B. a chemical change. C. both a physical and chemical change. D. neither a physical nor chemical change.

A. a physical change. The gold is still gold, it is now in a liquid state.

Each spectral line in an atomic spectrum represents A. a specific frequency of light emitted by an element. B. one of the many colors of an element. C. a pattern characteristic of the element. D. all of the above.

A. a specific frequency of light emitted by an element. Many lines make up a pattern that is characteristic of the element, so choice C doesn't fly. Interestingly, the line shape of each spectral line is an image of a thin slit in the spectroscope.

Excitation is the process whereby A. electrons are boosted to higher energy levels in an atom. B. atoms are charged with light energy. C. atoms are made to shake, rattle, and roll. D. none of the above.

A. electrons are boosted to higher energy levels in an atom.

When an atom is excited, its A. electrons are boosted to higher energy levels. B. atoms are charged with light energy. C. atoms are made to shake, rattle, and roll. D. none of the above.

A. electrons are boosted to higher energy levels.

The most abundant element in the universe is: A. hydrogen. B. helium. C. oxygen. D. iron.

A. hydrogen. The second most abundant element is helium.

The atomic number of an element matches the number of A. protons in the nucleus of an atom. B. electrons in an ion of the same atom. C. neutrons in the nucleus. D. nucleons in the nucleus.

A. protons in the nucleus of an atom.

When an element ejects an alpha particle, the atomic number of the resulting element A. reduces by 2. B. reduces by 4. C. increases by 2. D. increases by 4.

A. reduces by 2. An alpha particle (a helium nucleus) has atomic number 2. So, ejection of an alpha particle means a loss of two protons. Hence, the atomic number of the element is lowered by two.

The shell model of the atom views electrons as occupying A. shells. B. three-dimensional orbitals. C. circular or elliptical orbits. D. standing waves.

A. shells.

The lanthanides are much like a group of elements because A. they share similar properties. B. their atomic numbers are consecutive. C. they extend the height of the periodic table. D. they are all metallic.

A. they share similar properties.

A certain element emits 1 alpha particle, and its products then emit 2 beta particles in succession. The atomic number of the resulting element is changed by A. zero. B. -1. C. -2. D. none of the above.

A. zero. Removal of the alpha decreases atomic number by 2, but removal of two electrons increases it by 2, so there is no net change in atomic number.

Which is larger: an arsenic atom or a sulfur atom?

An Arsenic Atom

An archaeological dig uncovers an ancient spear whose wooden handle contains 1/8 the radioactive carbon of a fresh piece of wood. About how old is the spear? A. 11,520 years old B. 17,280 years old C. 46,080 years old D. 23,040 years old

B. 17,280 years old If 1 half-life reduces the C-14 by 1/2, then 2 reduces it by 1/4 and 3 reduces it by 1/8, so the answer is: 3 x 5760 years = 17,280 years

A nucleus with an atomic number of 30 and a mass number of 65 must have A. 30 neutrons. B. 35 neutrons. C. 65 neutrons. D. all of the above.

B. 35 neutrons. Be sure to distinguish between neutron and nucleon. A neutron is a nucleon, as is a proton.

A nucleus with an atomic number of 44 and a mass number of 100 must have: A. 44 neutrons. B. 56 neutrons. C. 100 neutrons. D. none of the above.

B. 56 neutrons. Be sure to distinguish between neutron and nucleon. Of the 100 nucleons in the nucleus, 56 are neutrons. A neutron is a nucleon, as is a proton.

Which of the following particles are electrically neutral? A. Proton. B. Neutron. C. Electron. D. All of the above.

B. Neutron.

How many periods are there in the periodic table? A. One. B. Seven. C. Eighteen. D. Thirty-Six.

B. Seven. A period is a set of elements whose physical and chemical properties gradually change with each increase in atomic number. Elements within the same horizontal row in the periodic table are in a single period.

Tarnishing a piece of silver would be... A. a physical change. B. a chemical change. C. both a physical and chemical change. D. neither a physical nor chemical change.

B. a chemical change. Tarnish transforms pure silver, Ag, to silver sulfide, Ag2S.

The transformation of oxygen, O2, into ozone, O3, is an example of A. a physical change. B. a chemical change. C. both a physical and chemical change. D. neither a physical nor chemical change.

B. a chemical change. The same kinds of atoms are involved but how they are arranged is completely different. Thus, a new substance has been formed.

In the relationship E , the symbol stands for the frequency of emitted light, and E stands for the A. potential energy of the electron emitting the light. B. energy of the photon. C. kinetic energy of the photon. D. all of the above.

B. energy of the photon. For those answering choice A, note that the energy of the photon is equal to the difference in energy levels for the electron emitting the photon—not its value at one energy level.

When an element ejects a beta particle, the atomic number of that element A. reduces by 1. B. increases by 1. C. reduces by 2. D. increases by 2.

B. increases by 1. A beta particle (an electron) has electric charge -1. So, ejecting a beta particle means a loss of one unit of charge and a gain of 1 in atomic number. In beta emission, a neutron ejects an electron and becomes a proton. So, the element adds a proton to its nucleus.

The periodic table lists: A. less than 100 elements. B. more than 100 elements. C. many more than 100 molecules. D. thousands of ions, atoms, and molecules.

B. more than 100 elements.

A quantum of light is called a A. proton. B. photon. C. both of the above. D. neither of the above.

B. photon.

The symbol CO denotes A. the element cobalt. B. the combination of carbon and oxygen. C. oxidized cobalt. D. actually, all of the above.

B. the combination of carbon and oxygen. Only the first letter of an atomic symbol is capitalized. For example, helium is He, lithium is Li, Co is cobalt, and so forth. Oxygen is simply O and carbon C.

Electrons in the outermost shells of atoms are called A. outer electrons. B. valence electrons. C. chemical electrons. D. wave electrons.

B. valence electrons.

Which of the following is a quantum number? A. 0.01 B. 0.1 C. 1 D. 1.5

C. 1 Integers only

Which of the following is a quantum number? A.0.02 B. 0.2 C. 2 D. 2.5

C. 2 Quantum numbers are integers only

Which of these has the greatest energy per photon? A. Red light. B. Green light. C. Blue light. D. All have the same.

C. Blue light. In accord with E , the highest frequency light has the greatest energy per photon.

How many groups are there in the periodic table? A. One. B. Seven. C. Eighteen. D. Thirty-Six.

C. Eighteen. A group is a set of elements with similar physical and chemical properties. Elements within the same vertical column in the periodic table are in a group (or sometimes called a family).

Which of these photons has the greatest energy? A. Infrared. B. Visible. C. Ultraviolet. D. All have the same.

C. Ultraviolet.

Each spectral line in a spectrum represents A. a pattern characteristic of the element. B. one of the many colors comprising an element. C. a specific frequency of light emitted by an element. D. all of the above.

C. a specific frequency of light emitted by an element. Many lines make up a pattern that is characteristic of the element, so choice A doesn't fly. Interestingly, the line shape of each spectral line is an image of a thin slit in the spectroscope.

Any material that is made up of only one type of atom is classified as: A. a substance. B. molecularly pure. C. an element. D. an isotope.

C. an element

Any material that is made up of only one type of atom is classified as: A. a substance. B. molecularly pure. C. an element. D. an isotope.

C. an element.

The atomic number of an element matches the number of: A. protons in the nucleus of an atom. B. electrons in a neutral atom. C. both of the above. D. none of the above.

C. both of the above. When the atomic number doesn't match the number of electrons, the atom is an ion.

Uranium-235, uranium-238, and uranium-239 are different A. elements. B. ions. C. isotopes. D. nucleons.

C. isotopes. U-235 is the isotope that can undergo fission.

The mass number of an element refers to the number of A. protons in its nucleus. B. neutrons in its nucleus. C. nucleons in its nucleus. D. all of the above.

C. nucleons in its nucleus. Nucleons include protons and neutrons. Atomic number refers to the number of protons; mass number refers to the number of nucleons (protons + neutrons).

A certain isotope has a half-life of one day. This means the amount of that isotope remaining at the end of two days will be A. zero. B. one eighth. C. one quarter. D. half.

C. one quarter. And after three days, the amount remaining will be one eighth.

When an atom undergoes radioactive decay, it A. becomes an ion of the same element. B. becomes an isotope of the same element. C. turns into a completely different element. D. may or may not turn into a completely different element.

C. turns into a completely different element.

Radiometric Dating

Carbon dating used for plants and animals Based upon ratio of carbon-12 to carbon-14 Half-life of carbon-14 is about 5760 years Method not exact due to fluctuations in Earth's carbon-14 production

What is the name of the compound with the formula CBr4? A. Chrobrofor B. SeeBer4 C. Carbon bromide D. Carbon tetrabromide.

D. Carbon tetrabromide.

A nucleus with an atomic number of 10 and a mass number of 22 must have A. 10 protons. B. 12 neutrons. C. 22 nucleons. D. all of the above.

D. all of the above.

Nuclear Fission

Energy released is in the form of kinetic energy of fission fragments that fly apart from one another, with some energy given to ejected neutrons, and the remainder given to gamma radiation.

How to name a compound

Guideline 1 -Start with the element farthest to the left in the periodic table. -For the element to the right, add the suffix -ide. -Example: NaCl Sodium Chloride With different possible combinations of elements, use prefixes to remove ambiguity. (Mono- 1; Di- 2; Tri-3; Tetra- 4)

Of the atoms sodium, Na; magnesium, Mg; and aluminum, Al, one tends to lose three electrons, another tends to lose two electrons, and another tends to lose one electron. Rank these atoms in order of the number of electrons they tend to lose, from fewest to most.

Na (1) < Mg (2) < Al (3)

Atom

The fundamental unit of an element

Elemental formula:

Used to show the proportion by which atoms combine to form an element. Oxygen--- O2 Sulfur----S8

Chemical formula:

Used to show the proportion by which elements combine to form a compound.

Physical change:

a change in the physical properties of a substance.

Neutrons

accompany protons in the nucleus; have about the same mass as protons but no charge, so are electrically neutral

Types of radiation:

alpha ()- carries positive electrical charge beta ()- carries negative electrical charge gamma ()- carries no charge

Spectroscope

an instrument that separates and spreads light into its component frequencies allows analysis of light emitted by elements when they are made to glow—identifies each element by its characteristic pattern Each element emits a distinctive glow when energized and displays a distinctive spectrum.

Gamma rays:

are high-frequency electromagnetic radiation are emitted when a nucleus in an excited state moves to a lower energy state are more harmful than alpha or beta particles are most penetrating because they have no mass or charge are pure energy, greater per photon than in visible or ultraviolet light and X-rays are unaffected by magnetic and electric fields, and therefore interact via direct hit with an atom

Electrons

are identical; repel electrons of neighboring atoms; have electrical repulsion that prevents atomic closeness

Protons

carry a positive charge—same quantity of charge as electrons

Alpha particle:

consists of two protons and two neutrons (a helium nucleus) loses energy quickly during interaction can be stopped easily by a few pieces of paper due to its large mass and double positive charge does not normally penetrate lightweight material (paper, clothing) causes significant damage to the surface of a material (living tissue) due to great kinetic energy picks up electrons and becomes harmless helium when traveling through air is deflected in the presence of magnetic or electric fields

A physical property

describes the look or feel of a substance.

A chemical property

describes the tendency of a substance to transform into a new substance.

Beta particle:

is an ejected electron from a neutron has both a smaller mass and electric charge than an alpha particle, and moves faster loses energy at a slower rate in air and travels farther before stopping can be stopped by several sheets of aluminum foil penetrates fairly deeply into skin (potential for harming or killing living cells) once stopped, becomes an ordinary electron is deflected in the opposite direction to an alpha particle in the presence of magnetic and electric fields

Atomic spectrum

is an element's fingerprint—a pattern of discrete (distinct) frequencies of light.

Atomic number

is the number of protons in each element listed in the periodic table.

Half-life:

is the rate of decay for a radioactive isotope. is the time required for half of an original quantity of an element to decay. is constant and independent of any physical or chemical change the atom may undergo. can be calculated at any given moment by measuring the rate of decay of a known quantity using a radiation detector.

Total number of neutrons in isotope =

mass number - atomic number

Both protons and neutrons are _______

nucleons

Radioactivity

process whereby unstable atomic nuclei transform and emit radiation. natural background radiation that originates in Earth and space (cosmic rays from the Sun and stars). more intense at higher altitudes.

Isotopes

refers to atoms of the same element that contain the same number of protons but different numbers of neutrons in the nucleus identified by mass number, which is the total number of protons and neutrons in the nucleus differ only in mass and not by electric charge; therefore, isotopes share many characteristics

Chemistry is. . .

the study of matter and the transformations it can undergo. the "central" science. a "materials" science.

Chemical change

the transformation of one or more substances into others.

Atomic mass

total mass of the atom(s) [protons, neutrons, and electrons] listed in periodic table as atomic mass unit

Quantum Hypothesis

warm bodies emit radiant energy in discrete bundles called quanta. Energy in each energy bundle is proportional to the frequency of radiation. When an electron in any energy level drops closer to the nucleus, it emits a photon of light.