Chapter 2 practice questions

proton

+1

electron

-1

Neutron

0

If a solution has a pH of 3, then its hydrogen ion concentration is which of the following?

1 x 10-3 mol/L

An electrically neutral atom has an atomic number of 11 and an atomic mass of 23. This atom has ___ protons, ___ neutrons, and ___ electrons.

11, 12, 11

This question refers to elements in the main groups of the periodic table. According to the octet rule, if an atom's first energy level is the outermost shell then it is stable with ___ electrons and if an atom has any other energy level as its outermost shell then it is stable with ___ electrons.

2, 8

If a solution has a [H+] of 10-9 mol/L, then its pH is

9

Molecules that are more polar tend to have which of the following characteristics? A lower heat of vaporization A lower specific heat A higher specific heat A higher heat of vaporization

A lower specific heat A higher specific heat A higher heat of vaporization

Which of the following best describes how temperature affects the rate of a chemical reaction (assume care has been taken that the temperature is not too high as to destroy the reactants)? As temperature increases, the reaction rate decreases. As temperature increases, the reaction rate first decreases and then increases. As temperature increases, the reaction rate increases. As temperature increases, the reaction rate first increases and then decreases.

As temperature increases, the reaction rate increases.

hydrogen bond

Attraction between a covalently bound H atom with a slight positive charge and another covalently bound atom with a slight negative charge

The four most abundant elements in living organisms are ___, ___, ___, and ___.

C, N, O, and H

A sodium atom that has lost an electron and has an overall positive charge is an example of which of the following? Isotope Isomer Anion Cation

Cation

Consider a large protein molecule that has some parts that are highly hydrophobic. When placed in a water solution, the protein folds in a globular shape, such that all the hydrophobic portions are inside the molecules, away from water. This is an example of which of the following?

Hydrophobic exclusion

Which property of water strongly affects the overall shape of many biological molecules, such as protein, and DNA?

Hydrophobic exclusion

Within an atom, where are electrons found? In orbitals that surround the nucleus Concentrated at one end of the atom with the nucleus at the opposite end Evenly distributed throughout the atom In orbitals located inside the nucleus In the nucleus

In orbitals that surround the nucleus

How are ions formed? Ions are formed when atoms lose or gain one or more neutrons. Ions are formed when atoms lose or gain one or more electrons. Ions are formed when atoms lose or gain one or more protons.

Ions are formed when atoms lose or gain one or more electrons.

When an acid is dissolved in water, how does it change the solution's pH?

It decreases the solution's pH by releasing protons in the solution.

What is true of a molecule of gaseous hydrogen (H2)? It has one partial positive charge and one partial negative charge which are balanced. It has no net charge. It has a partial positive charge.

It has no net charge.

Select the reasons that the molecule formed by two hydrogen atoms (H2) is stable. It has no net charge. It has no unpaired electrons. It is held together by an ionic bond. The octet rule is not satisfied. It is held together by a covalent bond.

It has no net charge. It has no unpaired electrons. It is held together by a covalent bond.

What does it mean when we say water is adhesive? It is attracted to nonpolar molecules. It is held together by strong covalent bonds. It is attracted to other polar molecules and ions. It is attracted to each other.

It is attracted to other polar molecules and ions.

Electrons that are closer to the nucleus always have which of the following? Less kinetic energy Greater mass Less potential energy More potential energy

Less potential energy

A group of atoms held together by chemical bonds in a stable association is called which of the following? Crystal Molecule Isotope Ion

Molecule

Which of the following molecules are nonpolar? N2 H2O CH4 O2

N2 CH4 O2

Isotopes are atoms of the same element that differ in the number of which of the following? Protons Neutrons Orbitals Electrons

Neutrons

hydrophobic interaction

Nonpolar regions of a molecule are forced together in order to minimize contact with water molecules

Hydrophobic substances tend to do which of the following? Repel water Readily form hydrogen bonds with water Aggregate together when mixed with water in order to minimize contact with water Assume shapes that minimize contact with water

Repel water Aggregate together when mixed with water in order to minimize contact with water Assume shapes that minimize contact with water

When the pH of a solution rises by 1 which of the following happens?

The [H+] decreases 10-fold

In a neutral atom, the number of electrons is equal to which of the following? The atomic number minus the atomic mass The atomic mass minus the atomic number The atomic number The atomic mass

The atomic number

Which of the following statements about polar molecules are true? The distribution of electrical charge is not uniform. They are electrically neutral. They have regions of partial positive charge or regions of partial negative charge, but not both. They have the same number of protons and electrons.

The distribution of electrical charge is not uniform. They are electrically neutral. They have the same number of protons and electrons.

Which of the following statements about nonpolar molecules are true? They have regions of partial positive charge and regions of partial negative charge. Some can form hydrogen bonds with polar molecules. The distribution of electrical charge is uniform. They are electrically neutral.

The distribution of electrical charge is uniform. They are electrically neutral.

Why does the rate of a reaction increase as the concentration of reactants increases? The reactants move faster. The reactants move slower. The reactants collide with each other more frequently. The reactants collide with each other less frequently.

The reactants collide with each other more frequently.

Electrons with the same potential energy always occupy which of the following? The same orbit The same orbital The same energy level

The same energy level

Atoms are chemically the most stable when which of the following occurs? Neutrons and electrons are in equal numbers. Their outer shell is full. They reside in the middle of the periodic table. They have six electrons in their outermost shell.

Their outer shell is full.

A neutral atom has no net electrical charge. Why? There are equal numbers of protons and electrons in the atom. The atomic mass and the atomic number are equal. There are equal numbers of protons and neutrons in the atom There are equal numbers of electrons and neutrons in the atom.

There are equal numbers of protons and electrons in the atom.

Choose all statements that describe atoms that have unfilled electron shells? They are chemically reactive. They can form bonds with other atoms They are located in the far-right column of the periodic table. They are chemically inert. They can form chemical compounds.

They are chemically reactive. They can form bonds with other atoms They can form chemical compounds.

The evaporation of water from body surfaces can significantly cool an organism. This is due to what property of water? The lower density of ice Water's solubility Water's high heat of vaporization Water's cohesive properties

Water's high heat of vaporization

Water helps living things maintain a relatively constant internal temperature and protects cells from overheating due to the heat released by chemical reactions. What property of water is responsible for that?

Water's high specific heat

Water helps living things maintain a relatively constant internal temperature and protects cells from overheating due to the heat released by chemical reactions. What property of water is responsible for that? Water's adhesive properties Water's high specific heat Water's high heat of vaporization Water's density

Water's high specific heat

Many animals have adapted to cool themselves by sweating. Which property of water allows for this adaptation?

Waters high heat of vaporization

van der Waals attraction

Weak attraction between atoms due to oppositely polarized electron clouds

A substance that increases [H+] and decreases pH when it dissociates in water is called a(n

acid

The attraction of water to other polar substances is called

adhesion

Electrons in the same energy level ___. always have the same potential energy. have decreasing potential energy as they fill the level's orbitals. have increasing potential energy as they fill the level's orbitals.

always have the same potential energy.

Atoms with a net negative charge are known as ___, whereas atoms with a net positive charge are known as___ .

anions, cations

Valence electrons and their interactions determine the ___ properties of an element.

chemical

Because polar water molecules attract each other, water is said to be

cohesive

What type of bond is formed when 2 atoms share one or more pairs of valence electrons?

covalent

If an atom gains or loses a(n) ___, it acquires a net electrical charge and becomes an ion.

electron

Redox reactions involve a transfer of ___ from one atom to another.

electrons

Subatomic particles called ___ can be found at various distances from the nucleus

electrons

When a sugar crystal is placed in water, every time a sucrose molecule dissociates from the crystal, water molecules surround it in a cloud forming a(n) ___ shell that prevents it from associating with other sucrose molecules.

hydration

Substances that attract water are called ___ ("water-loving") while substances that repel water are called ___ ("water-fearing").

hydrophilic, hydrophobic

The tendency of nonpolar molecules to aggregate together in water is known as ___ exclusion.

hydrophobic

Elements possessing all eight electrons (two for helium) in their outer energy level are ___

inert, and noble gases

C12, C13, and C14 are examples of different ___

isotopes

high heat of vaporization

many hydrogen bonds must be broken for water to evaporate

solubility

many types of ions and molecules move freely in cells, permitting a diverse array of chemical reactions

Anything that has mass and occupies space is defined as ___

matter

A(n) ___ is made of two or more atoms held together by chemical bonds in a stable association. The atoms may or may not belong to the same element.

molecule

Electrons that are farther from the nucleus have ___. more kinetic energy more potential energy greater mass less potential energy less kinetic energy

more potential energy

Isotopes differ in the number of ___ they contain.

neutrons

Water tends to repel or exclude ___ molecules.

nonpolar

Generally speaking, an atom is made of a central ___ which is surrounded by orbiting ___

nucleus, electrons

An atom's electrons are typically found in regions called ___; those regions can be found at varying distances from the nucleus.

orbital

The term ___ is used to designate the process of an atom losing one or more electrons while undergoing a chemical reaction.

oxidation

Water carries two partial negative charges on the ___ atom and two partial positive charges, one on each ___ atom.

oxygen, hydrogen

Substances or mixtures of substances known as buffers, act in living things to resist changes in Blank

pH

Cohesion

plant leaves pull eater up from the roots

A(n) ___ covalent bond is formed by when one or more electron pairs are unequally shared between two atoms.

polar

Which bond is formed by an unequal sharing of one or more electron pairs?

polar

A cation has a net ___ charge, while an anion has a net ___ charge.

positive, negative

Among subatomic particles, a(n) ____ has a charge of +1, a(n) ____ has a charge of -1, and a(n) ____ has no charge.

proton, electron, neutron

Atomic number refers to the number of ___ in an atom.

protons

The atomic number of an element refers to the number of ___ in the atoms of that element. neutrons electrons protons orbitals

protons

By convention, when writing a chemical equation the ___ are listed on the left side of the arrow and the ___ are listed on the right side of the arrow.

reactants, product

During a chemical reaction, the substances we start out with, are called ___, and the substances we end up with, are called ___.

reactants, products

An atom participating in a chemical reaction gains one or more electrons. The process of gaining electrons in a reaction is called ___

reduction

covalent bond

sharing of electrons

Because of the many hydrogen bonds that form between its molecules, water has a very high ___ ___. This allows small insects to "walk on water."

surface tension

The property of ___ ___ is a measure of how difficult it is to stretch or break the surface of a liquid.

surface tension

Electrons in outer, unfilled energy levels are known as ___ electrons.

valence

high specific heat

water stabilizes the temperature of organisms and the environment

When 1 g of fructose is dissolved in 500 mL of water, ___ is the solvent and ___ is the solute.

water, fructose

less dense as a solid than as a liquid

aquatic organisms can survive below the frozen surface of ponds and lakes

ionic bond

attraction between oppositely charged atoms