Homework 2
Molecules that are more polar tend to have which of the following characteristics?
- higher specific heat - higher heat of vaporization
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 Blank______, an atomic mass of Blank______, and an overall charge of Blank______.
11, 23, +1
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 Blank______, an atomic mass of Blank______, and an overall charge of Blank______.
8, 17, 0
Atomic mass is measured in which of the following units?
Daltons
_________ atoms always have one proton.
Hydrogen
__________ atoms usually have no neutrons.
Hydrogen, (H) OR Protium
Which property of water strongly affects the overall shape of many biological molecules, such as protein, and DNA?
Hydrophobic exclusion
What does it mean when we say water is adhesive?
It is attracted to other polar molecules and ions.
Which of the following is the definition of the heat of vaporization of water?
The amount of energy needed to change 1 g of water from a liquid to a gas
In a neutral atom, the number of electrons is equal to which of the following?
The atomic number
Water has several properties important to life: high specific heat, high heat of vaporization, lower density in solid form (ice), ability to act as a solvent and to organize nonpolar molecules. What explains these properties of water?
The polar nature of water molecules
A neutral atom has no net electrical charge. Why?
There are equal numbers of protons and electrons in the atom.
The attraction of water to other polar substances is called ________.
adhesion
What do we call a substance that cannot be broken down into simpler substances by ordinary chemical means?
an element
The number and configuration of electrons determines an element's ______.
chemical properties
Because polar water molecules attract each other, water is said to be ________.
cohesive
A(n) __________ bond is formed when 2 atoms share one or more pairs of valence electrons.
covalent
Subatomic particles called __________ can be found at various distances from the nucleus
electrons
The chemical behavior of an atom is determined by the number and configuration of its ______.
electrons
In living organisms, almost all chemical reactions are catalyzed by protein catalysts called ___________.
enzymes
In living systems, which of the following catalyze almost every chemical reaction necessary for life?
enzymes
If two atoms are joined by a polar covalent bond, the shared electrons will tend to stay closer to the atom with ______.
higher electronegativity
_________can be defined as any substance that has mass and occupies space.
matter
A(n) ________ 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
Generally speaking, an atom is made of a central ________________ which is surrounded by orbiting _____________.
nucleus; electrons
Substances or mixtures of substances known as buffers, act in living things to resist changes in ______.
pH
The negative logarithm of the hydrogen ion concentration of a solution is known as its ______.
pH
If two atoms are joined by a polar covalent bond, the atom with the lower electronegativity will have a partial __________ charge.
positive
Atoms of the same element always have the same number of __________ in the nucleus, 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
The atomic mass of an atom is equal to the sum of the masses of its _______ , and __________.
protons and neutrons
Which subatomic particles determine the atomic mass of an atom?
protons and neutrons
The three main types of subatomic particles are _____ , _____, and _____.
protons, neutrons, and electrons
Chemical reactions that involve a transfer of electrons from one atom to another are called ___________ reactions.
redox
The __________ of a substance is a measure of how rapidly its individual molecules are moving.
temperature
If two atoms have the same number of protons in their nucleus, you can conclude for sure that they ________.
are atoms of the same element
A(n) _________ is a substance or a mixture of substances that act to resist changes in pH.
buffer
