Chapter 2 biology

buffer

A material that resists a change in pH is called a(n) _____.

one of the atoms sharing electrons is much more electronegative than the other

A covalent bond is likely to be polar if _____.

Element

A substance that cannot be broken down into other substances by ordinary chemical procedures is known as a(n) _____.

25

About ______ elements are believed to be essential to humans, including elements that are required only in trace amounts.

lower hydrogen ion concentration and increase the pH

Adding a base tends to _____ of a solution.

Electrons

An atom and an ion of the same element differ in the number of _____.

ice floats

Because the molecules of water are farther apart in ice than in liquid water, _____.

Chemical Reactions

Breaking existing chemical bonds to form new ones

Surface Tension

Creates the skin-like surface formed due to the polar nature on the molecular level

has a completely filled outermost shell

For most atoms, a stable configuration of electrons is attained when the atom __________.

isotopes

Have the same number of protons and behave identically in chemical reactions, but they have different number of neutrons

All are properties related to hydrogen bonding

How are cohesion and surface tension related to the chemical properties of water?

One atom gives up an electron to a second atom

How are ionic bonds formed?

Cohesion

Molecules of the same kind stick together

determine hot spots of metabolic activity

Positron-emission tomography (PET) is a technique that doctors may use to _____.

Mass Number

Sum of number of neutrons and protons in the nucleus

polar covalent bond

The atoms in a water molecule shown below are held together by which type of bond?

Adhesion

The attraction among molecules of DIFFERENT substances

2

The innermost electron shell of an atom can hold up to _____ electrons.

increase and lower the pH

The levels of carbon dioxide are expected to _____ of our oceans.

polar

The most widely effective solvent for organisms is a material that is _____.

equals the total number of electrons in the orbital shells

The number of protons in an uncharged atom__________________________.

uncharged

The number of protons is equal to the number of electrons ___________ atom.

Atomic Mass/Atomic Weight

The number of protons plus neutrons in an atom, represented as an average of all naturally occurring forms of the element, is known as

electronegativity

The tendency of an atom to pull electrons toward itself is referred to as its ____________________?

Compounds

They contain two or more elements in a fixed ratio to each other.

Protons

Two atoms of the same element must have the same number of _____.

heating water absorbs energy by disrupting the hydrogen bonds before evaporation can occur

Water can resist temperature change because _____.

the number of electrons in the outermost electron shell

What determines the types of chemical reactions that an atom participates in?

donates hydrogen ions to solutions

What is an acid?

Hydrogen Bond

What name is given to the bond between water molecules? (Weak Interaction)

Aqueous solution

When water is the solvent

the hydrogen ion concentration increases and lowers the pH

When you add acid to a solution, _____.

Carbon, Oxygen, Hydrogen, and Nitrogen

Which four elements are the primary components of important biological molecules, such as proteins, carbohydrates, and lipids? These four elements make up 96% of the human body.

Protons

Which of the following subatomic particles contributes toward the atomic mass of hydrogen?

Neutrons

Which of the following subatomic particles has appreciable mass and lacks a charge/electrically neutral?

Ions

__________ are charged atoms

Trace Elements

also called micronutrients, are any chemical element required by living organisms in miniscule amounts, but cells require them to survive.

Polar Molecule

has unequal distribution of charges

Ionic Bond

involves an attraction between ions of opposite charge

solution

is a liquid consisting of a uniform mixture of two or more substances

base

is a substance that reduces the hydrogen ion concentration of a solution

Atomic Number

is the number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table.

Polar covalent bonds

share electrons unequally, so that one part of the molecule has a negative pole and one part has a positive pole.

chemical reaction

the breaking and forming of chemical bonds that leads to a change in the composition of matter.

Covalent

this type bond occurs when two or more atoms share one or more pairs of electrons.