Chapter 2: Molecules and Water

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

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

Match the correct answers. Covalent bond > Ionic bond > Hydrogen bond > Hydrophobic interaction > Van der Waals attraction > - Sharing electrons - Attraction between oppositely charged atoms - Attraction between a covalently bound H atom with a slight positive charge and another covalently bound atom with a slight negative charge. - Nonpolar regions of a molecule are forced together in order to minimize contact with water molecules - Weak attraction between atoms due to oppositely polarized electron clouds

- Covalent bond > Sharing electrons - Ionic bond > Attraction between oppositely charged atoms - Hydrogen bond > Attraction between a covalently bound H atom with a slight positive charge and another covalently bound atom with a slight negative charge. - Hydrophobic interaction > Nonpolar regions of a molecule are forced together in order to minimize contact with water molecules - Van der Waals attraction > Weak attraction between atoms due to oppositely polarized electron clouds

What is the charge of a hydroxide ion? - -2 - +1 - +2 - -1

-1

Match each subatomic particle with its electrical charge. 0 > +1 > -1 > - neutron - proton - electron

0 > neutron +1 > proton -1 > electron

A hydrogen ion, formed during the dissociation of water, has a charge of ____. - -2 - +1 - +2 - -1

1

Which of the following bonds involves the sharing of one or more pairs of electrons? - A covalent bond - A ionic bond - A hydrogen bond

A covalent bond

Where are the valence electrons of an atom found? - In the innermost energy level only - In the outermost energy level only - In the 2p orbitais only - In all energy levels

In the outermost energy level only

How are ions formed? - 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 neutrons

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

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

Neutrons (Reason: isotopes of the same element have the same number of protons, and therefore, the same number of electrons. The differ in the number of neutrons.)

Choose the four most abundant elements in living organisms. - Phosphorus - Nitrogen - Calcium - Oxygen - Water - Hydrogen - Carbon

Nitrogen, Oxygen, Hydrogen, Carbon

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

Oxygen, Hydrogen

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

They are electrically neutral, They have the same number of protons and electrons

What does it mean when we say water is adhesive? - Water molecules are attracted to nonpolar molecules - Atoms in water molecules are held together by strong covalent bonds - Water molecules are attracted to other polar molecules and ions - Water molecules are attracted to each other

Water molecules are attracted to other polar molecules and ions

Buffers can stabilize the pH of solutions because they ____ hydrogen ions when an acid is added and _____ hydrogen ions when a base is added.

absorb, release

The attraction of water molecules to the molecules of other polar substances is called ____.

adhesion

An atom is composed of a central nucleus which is surrounded by which orbiting particles? - Electrons - Ions - Neutrons - Protons

electrons

The chemical behavior of an atom is determined by the number of configuration of its ____. - isotopes - protons - electrons - neutrons

electrons

The attraction between the partially negative oxygen atom of one water molecule and the partially positive hydrogen atom of another water molecules is called a(n) ____ bond.

hydrogen

Substances that attract water are called ____ (water-loving), while substances that repel water are called ____ (water-fearing).

hydrophilic, hydrophobic

Atoms, in which the number of electron does not equal the number of protons, are called ____.

ions

The oxygen atom in a water molecules carries two partial ____ charges while each hydrogen atom carries a partial ____ charge.

negative, positive

Isotopes differ in the number of ____ they contain.

neutrons

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

nucleus, electrons

A hydrogen bond can form between the partially negative ____ atom of one water molecule and the partially positive ____ atom of another water molecule.

oxygen (O), hydrogen (H)

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

oxygen, carbon, hydrogen, and nitrogen

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

proton, electron, neutron

Which of the following statements about non polar molecules are TRUE? - Some can form hydrogen bonds with polar molecules - They are electrically neutral - They have regions of partial positive charge and regions of partial negative charge - The distribution of electrical charge within a molecule is uniform

they are electrically neutral , the distribution of electrical charge within a molecule is uniform

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

valence

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

cohesive

Which of the following best describes the entire acidic range of the pH scale? - pH values between 1 and 7 - Any pH value below 7 - pH values between 0 and 6 - pH values between 1 and 6

Any pH below 7

Which of the following best describes the entire alkaline range of the pH scale? - pH values between 8 and 14 - Any pH value above 7 - pH values between 6 and 14 - pH values between 7 and 13

Any pH value above 7

Water is cohesive because water molecules are ____.

attracted to each other

Water is cohesive because water molecules are ____. - held together by strong covalent bonds - attracted to each other - attracted to other (not water) polar molecules - attracted to ions

attracted to each other

Buffers stabilize pH by releasing hydrogen ions when a(n) ____ is added and absorbing hydrogen ions when a(n) ____ is added.

base, acid

The number and configuration of electrons determines an element's ____. - radioactivity - chemical properties - isotopic properties

chemical properties