Bio Ch 2

What is the charge of a hydroxide ion?

-1

A hydrogen ion, formed during the dissociation of water, has a charge of

1

Beer has a pH of 3, therefore its H+ concentration is __ times greater than a solution with a pH of 5

100

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

An atom has 11 protons, 12 neutrons, and 10 electrons. This atom has an atomic number of ___, and atomic mass of____, and an overall charge of ____

11, 23, +1

In a single covalent bond, __ total electron are shared

2

In a double covalent bonfd, __ total electorns are shared

4

An electrically neutral atom has an atomic number of 6 and an atomic mass of 14. This atom has ___ protons, ____neutrons, and ____electrons.

6, 8, 6

An atom has 8 protons, 9 neutrons, and 8 electrons. This atom has an atomic number of ___, an atomic mass of ___, and an overall charge of___

8, 17, 0

Molecules that are more polar tend to have which of the following characteristics?

A higher heat of vaporization A higher specific heat

Water boils at a higher temperature than a non-polar solvent like ether because

A large amount of energy is required to break the many hydrogen bonds that restrict the movement of individual water molecules

A __ acts to decrease the hydrogen ion concentration of a solution

Base

A ___ acts to maintain a relatively stable concentration of hydrogen ions in a solution

Buffer

A ___ is a substance (or mixture of substances) that acts ro resist changes in PH

Buffer

Adhesion

Capillarity Water readily dissolves other polar molecules Water readily dissolves table salt (NaCl) Paper towels readily absorb water

One of the 4 most common elements in living organisms

Carbon, hydrogen, oxygen, nitrogen

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

Cation

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

Chemical

The number and configuration of electrons determines an elements

Chemical Properties

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

Cohesive

A ____ bond is formed when 2 atoms share one or more pairs of valence electrons

Covalent

In structural formulas, each solid between atomic symbols represnts a single ___ bond

Covalent

True, disrcrete molcules form when atoms are connected by

Covalent Bonds

As the hydrogen ion concentration of a solution increases, the pH __

Decreases

The affinity of an atom for an electron is also known as which of the following?

Electronegativity

An atom is composed of a central nucleus which is surrounded by which orbiting particles?

Electrons

Redoc reactions involve a transfer of ___ from one atom to another

Electrons

The smaller spheres in the simple "Bohr Model" of atoms shown here represent ___

Electrons

A substance that cannot be broken down into simpler substances by ordinary chemical means is called an

Element

In living systems, which of the following catalyze almost every chemical reaction necessary for life?

Enzymes

A neutral oxygen atom (atomic #=8) has 8 electrons located in 2 different electron orbitals

False

Almost all of the mass of an atom is concentrated in its electrons

False

Hydrogen has only one neutron and no protons in its nucleus

False

The reactivity or chemical behavior of an atom depends primary on the number of neutrons it has

False

Ionic Bonds

Formed by an attraction between atoms with opposite charges Bond that holds NaCl Involves a transfer of one or more electrons from one atom to another Leads to the formation of a crystal lattice rather than distinct molecules Weakest type of bond shown

Which of teh following are molecular formulas?

H2, O2

Sodium vs. Chlorine and Carbon

Has 1 valence electron Most likely to lose an electron Lowest electronegativity Most likely to form a cation

Carbon vs. Sodium and Chlorine

Has 4 valence electrons Most likely to share electrons Most likely to form covalent bonds

Chlorine vs. Sodium and Carbob

Has 7 valence electrons Most likely to gain an electron Highest electronegativity Most likely to form an anion

The amount of energy required to change 1g of a substance from a liquid to a gas is called which of the following?

Heat of vaporization

Evaporation of water is often used to cool body surfaces

High heat of vaporization

A wide variety of substances can move freely and interact within cells

High solubility of ions and polar molecules

The temperature of living organisms is relatively stable

High specific heat

Cohesion

High surface tension Water is a liquid rather than a gas at room temperature High specific heat High heat of vaporization

If two atoms are joined by a polar covalent bond, the shared elctrons will tend to stay to the atom with

Higher electronegativity

Single Covalent Bond

Holds a molecule of hydrogen together Involves 2 atoms sharing 2 electrons Two chlorine atoms are held tg by this bond

Double Covalent Bond

Holds a molecule of oxygen together Involves 2 atoms sharing 4 electrons The strongest type of bond shown Carbon dioxide is held together by

___ atoms usually have no neutrons

Hydrogen

____________ atoms always have one proton.

Hydrogen

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 protiens, and DNA?

Hydrophobic Exclusion

Nonpolar molecules tend to aggregate or organize in ways that minimize their contact with water

Hydrophobic exclusion

As the pH of a solution increases, the concentration of ___ ions increases

Hydroxide

Lakes freeze from the top down, allowing fish and other life to survive below the surface

Ice is less dense than liquid water

As the hydrogen ion concentration of a solution decreases the pH __

Increases

Elements that present in trace amounts only

Iodine, Zinc

The atoms in NaCl are held together by what type of bond?

Ionic

Unlike ___ bonds, which produce a crystal lattice, ___ bonds are formed between 2 individual atoms, giving rise to true, discrete molecules

Ionic, covalent

Atoms, in which the number of electrons does not equal the number of protons, are called

Ions

How are ions formed?

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

What is true of a molecule of gaseous hydrogen (H2)?

It has no net charge

Why is the molecule H2 stable?

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

A Dalton is a unit of which of the following?

Mass

A ___ 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

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

Molecule

The pH of a solution is defined as the __ of the hydrogen ion concentration

Negative logarithm

Isotopes are atoms of the same element that differ in the number of which?

Neutrons

Isotopes differ in the number of ___ they contain

Neutrons

Which subatomic particles are located in the nucleus of an atom?

Neutrons and protons are

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

Nucleus, electrons

Which are structural formulas?

O=O, H-H

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

Orbitals

Among subatomic particles, a ____ has a charge of +1, a ____ has a charge of -1, and a ___ has no charge

Proton, electron, neutron

Within an atom, ___ and ____ have nearly equal masses, while ____ have a much smaller mass

Proton, neutrons, electrons

Atoms of the same element always have the same number of ___ in the nucelus, and this number is unique for that element

Protons

The atomic number of an element refers to the number of ___ in the atoms of that element

Protons

Atoms of different chemical elements can be differentiated based on the number of

Protons in the nucleus

The three main types of subatomic particles are

Protons, Neutrons, and electrons

Chemical reactions that involve a transfer of electrons from one atom to another are called ___ reactions

Redox

Not one of the 4 most common elements in living organisms but present in greater than trace amounts

Sodium, Chlorine, Calcium, Phosphorus, Potassium, Sulfur, Magnesium, Iron

The __ of a substance is a measure of how rapidly its individual molecules are moving

Temperature

Water has several properties to life: high specific heata, high heat of vaporization, lower desnity in solid form, ability to act as a solvent and to nonpolar molecules. What explains these properties of water?

The polar nature of water molecules

Almost all of the volume of an atom is empty space

True

An atom consists of a central nucleus surrounded by electrons that are in constant motion

True

Atomic orbitals represent probability distributions for electrons and come in a variety of shapes

True

Modern physics indicates that we cannot determine the exact location of a particular electron at any given time

True

The orbital of an electron is the volume of space where the electron is most likely to be found

True

What does it mean when we say water is ahesive?

Water molecules are attracted to other polar molecules and ions

When NaCl is formed

a sodium atom loses an electron, while a chlorine atom gains an electron

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

electron

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

electrons

Solid water is __ dense than liquid water

less

States of water from order of most dense to least dense

liquid, solid, gas

If atoms are joined by a polar covalent bond, the atom with the lower electronegativity will have a partial __ charge

positive

Electrons are maintained in their orbitals by their attraction to the positively charged nucleus

true

A __ acts to increase the hydrogen ion concentration of a solution

Acid

The attraction of water molecules to the molecules of other polar susbtances is called

Adhesion

A chlorine atom that has gained an electron has an overall negative charge is an example of an

Anion

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

Anions, Cations

If two atoms have the same number of protons in their nuclei, you can conclude for sure that they ___

Are atoms of the same element