3: The Chemistry of Life Flashcards
Module 1, Lesson 3
Life depends on the ____ of the molecules that make up cells.
Chemical properties
The smallest stable component of cells are…
Atoms
Atoms are made up of smaller, unstable particles called…
(three items)
Protons, neutrons, and electrons
What is the charge of a proton?
Positive
What is the charge of a neutron?
Neutral / no charge
What is the charge of an electron?
Negative
Protons and neutrons are located in an atom’s…
Nucleus
True or false:
Most of the volume of an atom is empty space.
True
An atom’s interactions with other atoms are influenced by its…
Electrons
The ____ represents atoms as a nucleus surrounded by rings representing orbitals.
Bohr model
A substance that can’t be broken down into another substance by chemical means is called an…
Element
The number of protons in an element is its…
Atomic number
The amount of a substance is its…
Mass
The force exerted by gravity on an object is its…
Weight
The sum of the masses of an atom’s protons and neutrons is its…
Atomic mass
Atomic mass is measured in…
Daltons
1 Dalton equals…
The mass of a proton or a neutron
Only ____ elements are regularly found in living systems.
12
Most of an organism’s mass is made up of…
(four items)
Carbon, oxygen, hydrogen, and nitrogen
Carbon-containing molecules are known as…
Organic molecules
Atoms of the same element that have different numbers of neutrons are called…
Isotopes
An electron’s energy level is related to its distance from the…
Nucleus
Energy is required to move an electron ____ the nucleus.
Away from
Moving an electron towards the nucleus ____ energy.
Releases
Electrons occupy discrete energy levels called…
Quanta
Chemical properties repeat every ____ elements.
Eight
Most elements necessary for life have no more than ____ valence electrons.
Eight
An atom’s chemical behavior is determined by…
How many of its valence positions are filled
Elements with all eight valence electrons tend to be…
Unreactive
The octet rule states that…
Atoms tend to want to establish completely full outer energy levels
Atoms with an electrical charge are called…
Ions
An ion that is positively charged (has more protons than electrons) is called a…
Cation
An ion that is negatively charged (has more electrons than protons) is called an…
Anion
In biological systems, reactive elements usally exist as…
Ions
A group of atoms held together in a stable association is called a…
Molecule
A molecule that contains atoms of two or more elements is called a…
Compound
Models that we can use to visualize molecules include…
(three items)
Bohr model, ball-and-stick model, space-filling model
A strong, stable interaction formed through the sharing of electron pairs is called a…
Covalent bond
True or false:
Electrons in covalent compounds are always shared equally.
False
When charge distribution is not equal in a covalently-bonded molecule…
The molecule has regions of partial positive and negative charge
A covalent bond or molecule where electrons are not shared equally is considered…
Polar
When atoms share more than one pair of electrons, a ____ forms.
Multiple bond
The strength of a covalent bond depends on…
The number of shared electrons
List the three main types of chemical bonds
- Covalent
- Ionic
- Hydrogen bonding
Which type of chemical bond is the strongest in living cells?
Covalent
Which type of chemical bond depends on attractions between positively and negatively charged ions?
Ionic
In ionic bonds, atoms form a ____ structure.
Crystal
Which type of chemical bond can be described as the “sharing” of a hydrogen atom?
Hydrogen bonding
(H-bonding)
Water molecules can form hydrogen bonds with which two kinds of molecules?
- Other water molecules
- Polar organic molecules
Water is able to form hydrogen bonds with other polar molecules because…
The charge distribution in these molecules in unequal.
Life functions around the properties of…
Water
List the properties of water that are critical for life on Earth.
(six items)
- Cohesion
- Adhesion
- High specifc heat
- High heat of vaporization
- Less dense in its sold form
- Acts as a solvent
Water is able to exist as a liquid on Earth because of the effects of…
Cohesion
Water molecules are attracted to ____ molecules.
Other polar
True or False:
Water will adhere to any material it can form hydrogen bonds with.
True
Adhesion can enable molecules to overcome…
Gravity
Because water has a high specific heat…
It heats slowly and loses heat slowly.
The heat required to raise the temperature of 1 gram of a substance by 1 degree Celsius is the…
Specific heat
Organisms can maintain a constant internal temperature because…
Water has a high specific heat
The energy needed to change 1 gram of a substance from a liquid to a gas is the…
Heat of vaporization
The heat of vaporization reflects the energy needed to break ____ bonds
Hydrogen
Organisms are able to stay cool in high temperatures because…
Water has a high heat of vaporization
Aquatic organisms are able to survive beneath ice in winter because…
Ice is less dense than water
If a molecule can interact with water, it will also be ____ in water.
Soluble
The molecule being dissolved in water is called the…
Solute
True or false:
Nonpolar molecules cannot form hydrogen bonds with water.
True
Molecules that cannot form hydrogen bonds with water are called…
Hydrophobic
Hydrophobic molecules ____ in water.
Cluster
Molecules that have both hydrophobic and hydrophilic regions are considered…
Amphipathic
True or false:
Water rarely forms ions spontaneously.
True
The pH scale measures the concentration of ____ in solution.
Hydrogen ions
A difference of 1 on the pH scale represents a ____ change in hydrogen ion concentration.
Tenfold
Solutions with a higher pH value have ____ hydrogen ion concentration.
Less
Solutions with a lower pH value have ____ hydrogen ion concentration.
Greater
The pH of pure water is…
7
A substance that dissociates in water to increase the concentration of hydrogen ions is called a(n)…
Acid
A substance that dissociates in water to decrease the hydrogen ion concentration is called a(n)…
Base
A substance that resists changes in pH is called a…
Buffer
Human blood is a…
Buffer system
In human blood, the acid component is…
Carbonic acid
In human blood, the base component is…
Bicarbonate
