Which of the following cannot be classified as a substance?

b. air

Examples of a physical change include

d. all of the above (freezing, melting, boiling, condensing, cutting, grinding)

Which statement is true of any chemical reaction?

d. The mass of the reactants equals the mass of the products.

Homogeneous mixtures

a. are always liquids.

Another name for a homogeneous mixture is

a. solution.

Which of the following statements describes a solid?

c. Its particles are packed tightly together.

Which of the following is a compound?

d. water.

Which of the following is an example of a chemical change?

a. cooking meat.

Which of the following is a heterogeneous mixture?

d. soil.

One difference between a mixture and a compound is that

b. A compound can be separated into its components by chemical means.

All types of matter

c. have mass and take up space.

How many significant figures are in the measurement 2103.2?

d. 5.

Which of these measurements is expressed to three significant figures?

b. 7.30 x 10^-7 km.

The closeness of a measurement to its true value is a measure of its

b. accuracy.

The temperature reading of -14⁰C corresponds to a Kelvin reading of

a. 259 K.

A student measures a volume as 250 mL, whereas the correct volume is 240 mL. What is the percent error?

b. -4.2%.

What is the density of an object having a mass of 8 g and a volume of 25 mL?

b. 0.32 g/mL.

Which of the following has the metric prefixes in order from largest to smallest?

d. kilo, deca, deci, nano.

What is the result of converting 48 m to centimeters?

c. 4800 cm.

A metric unit of volume is the

a. L.

Which of the following conversions is not correct?

d. 10 kg = 1 g.

A conversion factor:

d. all of the above.

Which of the following is the correct scientific notation for 0.000 008 62?

d. 8.62 x 10^-6.

According to the rules of significant figures, the number of digits that are estimates in measurement is

a. one.

How many centimeters are in 25 kilometers?

b. 2.5 x 10^5 cm.

What is the volume of 25.0 g of copper if the density of copper is 8.9 g/cm³?

a. 2.8 cm³.

Express the product of 4.0 x 10^-2 m and 8.1 x 10^2 m using the correct number of significant digits.

b. 3.0 x 10^2 m².

The sum of protons and neutrons in an atom equals the

d. mass number.

Light is emitted by an atom when

a. an electron drops from a higher to a lower energy level.

Dalton theorized that atoms are indivisible and that all atoms of an element are identical. Scientists now know that

c. atoms are all divisible.

Why did JJ Thomson believe that electrons (negatively charged particles) must be a part of the atom?

c. Cathode rays are attracted to positive magnetic plates.

What is the frequency of radiation with a wavelength of 5.00 x 10^-8 m?

d. 6.00 x 10^15 s^-1.

Calculate the wavelength of the yellow light emitted if the frequency of the radiation is 5.09 x 10^14 Hz.

b. 5.89 x 10^-7 m.

What is the energy of a photon of microwave radiation with a frequency of 3.20 x 10^11 s^-1?

c. 2.12 x 10^-22 J.

What is the frequency of a wavelength that has a photon energy of 3.84 x 10^-19 J?

a. 5.80 x 10^14/s.

Which of the following visible light colors has the greatest amount of energy?

c. violet.

Which of the following sublevels has the greatest amount of energy?

a. sublevel F.

The nucleus of an atom is

a. positively charged and has a high density.

What is the atomic number of an element?

The atomic number of an element is the number of protons in the nucleus of an atom of that element.

What is the mass number of an atom?

The mass number is the total number of protons and neutrons in an atom's nucleus.

What is a cation?

A cation is an atom or group of atoms that has a positive charge due to the loss of one or more electrons.

What is an anion?

An anion is an atom or group of atoms that has a negative charge due to the gain of one or more electrons.

What determines the identity of an element?

The identity of an element is determined by the number of protons in its atoms.

What are isotopes?

Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons.

What is electronegativity?

Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons.

What is the maximum number of electrons in the first three energy levels?

The maximum number of electrons in the first, second, and third energy levels is 2, 8, and 18, respectively.

What is the electron configuration for bromine?

The electron configuration for bromine is 1s2 2s2 2p6 3s2 3p5.

What is the significance of the periodic table?

The periodic table organizes elements based on increasing atomic number and groups elements with similar properties.

What are transition metals?

Transition metals are elements found in the d-block of the periodic table, known for their ability to form variable oxidation states.

What is the most electronegative element?

The most electronegative element is fluorine (F).

What is ionization energy?

Ionization energy is the energy required to remove an electron from an atom in its gaseous state.

What is the relationship between atomic size and electron configuration?

Atomic size generally increases down a group and decreases across a period due to increased nuclear charge and electron shielding.

What are diatomic molecules?

Diatomic molecules are molecules composed of two atoms, which can be of the same or different chemical elements.

What is the role of neutrons in an atom?

Neutrons contribute to the mass of an atom and help stabilize the nucleus by offsetting the repulsive forces between protons.

What is the average atomic mass?

The average atomic mass is the weighted average of the masses of an element's isotopes, based on their natural abundance.

What is the difference between a neutral atom and an ion?

A neutral atom has an equal number of protons and electrons, while an ion has a different number of protons and electrons, resulting in a charge.

What is the significance of the outermost energy level?

The outermost energy level determines an atom's chemical properties and its ability to bond with other atoms.

What is a quantum of energy?

A quantum of energy is the smallest discrete amount of energy that can be absorbed or emitted by an atom.

What is the difference between alpha, beta, and gamma radiation?

Alpha radiation consists of helium nuclei, beta radiation consists of electrons or positrons, and gamma radiation consists of high-energy photons.

What is the electron configuration for calcium?

The electron configuration for calcium is 1s2 2s2 2p6 3s2 3p6 4s2.

What is the trend of ionization energy across a period?

Ionization energy generally increases across a period due to increasing nuclear charge.

What is the trend of atomic radius down a group?

Atomic radius generally increases down a group due to the addition of energy levels.

What is a metalloid?

Metalloids are elements that have properties of both metals and nonmetals and are found along the zig-zag line on the periodic table.

What is the significance of the d-block in the periodic table?

The d-block contains transition metals, which are characterized by their ability to form various oxidation states and complex ions.

What is the energy change that accompanies the loss of an electron from an atom?

It is called ionization energy.

How does ionization energy change as you move down a group in the periodic table?

Ionization energy generally decreases as you move down a group.

Which of the following are listed in order of increasing electronegativity?

The correct order is sulfur, oxygen, fluorine.

Which of the following is NOT true about an alpha particle?

An alpha particle has a +1 charge (this is false; it has a +2 charge).

What characterizes an unstable nucleus?

An unstable nucleus may have too few or too many neutrons and loses energy by emitting radiation.

What happens during beta emission of an isotope?

The atomic number changes, but the mass number remains the same.

What are transuranium elements?

They are elements with atomic numbers above 92 and are sometimes radioactive.

What must a transmutation reaction involve?

A change in the number of protons in the nucleus of the atom.

Which of these is NOT a characteristic of most ionic compounds?

Ionic compounds typically have a low melting point (this is false; they usually have high melting points).

Which element would most likely form an ionic compound with chlorine?

Lithium would most likely form an ionic compound with chlorine.

What is the electron configuration of the fluoride ion (F-)?

The electron configuration is the same as that of the neon atom.

What is the charge on an aluminum ion after it loses its valence electrons?

The charge on the resulting ion is 3+.

What is true about cations and anions?

Cations form when an atom loses electrons, while anions form when an atom gains electrons.

What is the lowest whole-number ratio of ions in an ionic compound called?

It is called a formula unit.

What defines an ionic compound?

An ionic compound is electrically neutral and composed of anions and cations held together by ionic bonds.

What is the chemical formula for the ionic compound formed when calcium and nitrogen react?

The formula is Ca3N2.

What is a mixture of two or more elements, at least one of which is a metal?

It is called an alloy.

Which element does NOT exist as a diatomic molecule?

Helium does not exist as a diatomic molecule.

Which compound is NOT covalent?

KCl is not a covalent compound; it is ionic.

How many valence electrons does any halogen have?

Any halogen has 7 valence electrons.

What is a diatomic molecule with a triple covalent bond?

N2 is a diatomic molecule with a triple covalent bond.

What type of bond forms when a bonding pair of electrons is unequally shared?

The bond is called a polar covalent bond.

What are the possible shapes of a three-atom molecule?

A three-atom molecule can be linear, pyramidal, or tetrahedral.

What is the bond angle for any tetrahedral molecule?

The bond angle is approximately 109.5°.

How do the melting and boiling points of most molecular compounds compare to those of ionic compounds?

They are generally lower than those of most ionic compounds.

Which molecule contains the most polar bond?

HF contains the most polar bond.

Which diatomic molecule contains a single covalent bond?

F2 contains a single covalent bond.

What occurs when a covalent bond forms?

A covalent bond forms when atoms share electrons.

What is a coordinate covalent bond?

It is formed when both bonding electrons come from one atom.

What is the molecular shape of carbon tetrachloride (CCl4)?

The shape is tetrahedral.

What is the correct name for the ion Fe2+?

The correct name is iron (II) ion.