Test 1 ~ Bio 110 Intro to Cells and Atoms ~ Homework 2
Which of the following changes in the physical state of water require the input of energy?
1. Changing from solid to liquid 2. Changing from liquid to gas
Which of the following statements are true of a nonpolar covalent bond?
1. Electrons are shared equally between the two atoms. 2. The two atoms have similar electronegativity values.
An oxygen molecule (O2) contains a double bond, in which a total of ______ electrons are shared.
4
In humans, water comprises approximately ______ of body weight.
60-70%
What is a hydrolysis reaction?
A chemical reaction that utilizes water to break apart other molecules.
What are valence electrons?
An electron in the outermost shell of an atom that is available to share with other atoms. Such electrons allow atoms to form chemical bonds with each other.
Why are atoms likely to share electrons?
Because they have unfilled outer valence shells
What occurs during all chemical reactions?
Chemical bonds are broken or formed.
Consider the following covalent bonds. Pick the ones that are nonpolar
H-H, C-H, O-O
What type of bond occurs when a cation binds to an anion?
Ionic bond
Pure water can ionize into which of the following?
Positively charged protons (H+) and negatively charged hydroxide (OH-) ions
What is the atomic nucleus?
The center of an atom; contains protons and neutrons.
What is the atomic number?
The number of protons in an atom.
What is hydrophobic?
Water fearing. Refers to molecules that do not have partial charges and therefore are not attracted to water molecules.
What is a hydrophilic?
Water loving. Refers to molecules that contain ionic and/or polar covalent bonds and will dissolve in water.
Mass in neutrons and protons
are equal
Electronegativity is the ability of an atom to ______.
attract electrons
What are Non-polar Covalent Bonds?
bonds that form between atoms that have similar electronegativities
Living organisms minimize changes in their internal pH using compounds called ______. Multiple choice question.
buffers
Ice floats in liquid water because ice has a lower ______ than liquid water.
density
The measure of an atom's ability to attract electrons when in a bond with another atom is called its ______
electronegaticity
A pure substance made up of only one atom is called a(n) ______.
element
The capacity to do work is known as ______.
energy
Mass in electrons
have a smaller mass
High specific heat, surface tension, and cohesion are several properties of water involving ______ bonds.
hydrogen
When water is heated, the rate at which ______ bonds break increases, and water molecules are converted to the ______ state.
hydrogen, and gas
An atom that has gained or lost electrons, and thus has a net electric charge, is called a(n) ______
ion
Which state of water is the most dense?
liquid
Anything that contains mass and occupies space is called ______
matter
pH is defined as the ______, ______ to the base 10 of the ______ ion concentration.
negative, logarithm, H+
Isotopes of an element differ from one another in the number of ______ they contain.
neutrons
The region within an atom that surrounds the nucleus and in which there is a high probability of finding an electron is called an electron ______
orbital
By mass, the most abundant element in living organisms is ______.
oxygen
The ______ of a solution is the negative base 10 logarithm of the H+ concentration of the solution.
pH
A(n) ______ bond is formed when two atoms of different electronegativities share electrons.
polar covalent
Amphipathic molecules have both ______ regions and ______ regions.
poplar and nonpolar
Atoms are electrically neutral because they have equal numbers of ______, ______.
protons and electrons
To freeze water, energy is ______.
released
Substances dissolved in liquid are called ______.
solutes
A liquid that can dissolve substances is known as a(n) ______
solvent
Chemical bonds can form among atoms due to the presence of unpaired ______ electrons.
valance
In living organisms, most chemical reactions involve reactants and products that are dissolved in ______.
water
What four elements are the most common in living organisms?
1. Hydrogen 2. Carbon 3. Nitrogen 4. Oxygen
Which two particles are the primary determinants of an element's atomic mass?
1. Protons 2. Electrons
What happens when water freezes?
1. The rate of hydrogen bond breakage slows. 2. Water molecules are packed into a less dense formation. 3. The H2O molecules in ice are in a much more orderly arrangement than in the liquid state.
Which of the following statements are true of a polar covalent bond?
1. The two atoms in the bond share the electrons unequally. 2. The atoms in the bond differ in electronegativity.
Select all of the following that are true about atoms that have partially filled energy shells
1. tend to share, lose, or gain electrons. 2. can form compounds
What is a covalent bond?
A chemical bond in which two atoms share a pair of electrons.
What are electrons?
A negative charged particle found in the orbitals around an atomic nucleaus.
What is a neutron?
A neutral particle found in the nucleus of an atom.
What are protons?
A positive charged particle found in the nucleus of an atom.
Which component of humans has the greatest percent of water? Multiple choice question.
Lungs
What type of subatomic particle occurs in each different element in a unique number and is therefore used to identify specific elements?
Proton
Which of the following are subatomic particles that are confined to a small volume within the nucleus of an atom?
Protons and Neutrons
Which of the following statements is true of a polar covalent bond?
The shared electrons are closer to one nucleus than to the other.
Atoms of different chemical elements can be differentiated based on the number of ______.
protons in the nucleus
What are hydrogen bonds?
A weak chemical attraction between a hydrogen atom in a polar molecule and an electronegative atom in another polar molecule.
Which of the following covalent bonds are polar?
O-H and N-H
