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.