Ch.2 Flashcards
Anything that occupies space and has mass
Matter
What are the 3 physical states of matter?
Solid
Liquid
Gas
A substance that cannot be broken down to any other substances by chemical means.
Element
A substance consisting of two or more different elements combined in a fixed ratio.
Compound
Which 4 elements make up 96% of all living matter?
Oxygen
Carbon
Hydrogen
Nitrogen
Which elements are involved with bone formation?
Calcium and Phosphorus
Which elements are involved with nerve signaling?
Potassium, sodium, calcium and chlorine.
These are elements humans need but in minute quantities… .004%.
Trace Elements
This is an essential ingredient of a hormone produced by the thyroid gland.
Iodine
This is the smallest unit of matter.
Atoms
Atoms consist of which subatomic particles?
Protons
Neutrons
Electrons
What is the atomic #?
The number of protons
What is the mass #?
Sum of protons and neutrons in the nucleus.
These have the same number of protons but different neutrons and behave identically in chemical reactions.
Isotopes
One in which the nucleus decays spontaneously giving off energy and particles.
Radioactive Isotopes
A neutron has 7 protons, and its common isotope has 7 neutrons. A radioactive isotope of nitrogen has 9 neutrons. What is the atomic number and mass number of this radioactive nitrogen?
Atomic #- 16
Mass #- 16
Why are radioactive isotopes useful as tracers in research on the chemistry of life?
Organisms incorporate radioactive isotopes of an element into their molecules, and researchers can use special scanning devices to detect the presence of these isotopes in biological pathways or locations of the body.
Only ___ are directly involved in the chemical activity of an atom
Electrons
Two atoms, each with an unpaired electron in its outer shell actually share a pair of electrons.
Covalent Bonds.
An atoms attraction for shared electrons is called?
Electronegativity
The number of covalent bonds an atom can form depending on the number of additional electrons that are needed to fill its shell.
Bonding capacity
Electrons that are shared equally between atoms
Non-polar covalent bonds
Electrons that are not shared equally between atoms
Polar covalent bonds
An atom or molecule with an electrical charge resulting from a gain or loss of one or more electrons.
Ion
Two ions with opposite charges attract each other.
Ionic Bond
Explain what holds together the ions in a crystal of table salt (NaCl)?
Opposite charges attract. The positively charged sodium ions (Na) and the negatively charged ions (Cl) are held together by ionic bonds, attractions between oppositely charged ions.
Most strong chemical bonds are _____ bonds
Covalent
One of the most important types of weak bonds is called?
Hydrogen Bond
A type of weak chemical bond formed when the slightly positive hydrogen atom of polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule.
Hydrogen bond
The breaking of existing chemical bonds and formation of new ones.
Chemical reaction
The starting materials of a chemical reaction are called the?
Reactants
The ending materials of a chemical reaction are called?
Products
The tendency of molecules of the same kind to stick together.
Cohesion
The clinging of one substance to another substance.
Adhesion
A measure of how difficult it is to stretch or break the surface of a liquid.
Surface Tension
Energy associated with the random movement of atom and molecules
Thermal Energy
Thermal energy transfer from a warmer to a cooler body of matter.
heat
This measures the intensity of the heat. The average speed of molecules in a body of matter.
Temperature
____ must be absorbed to break hydrogen bonds, and ___ is released when hydrogen bonds form.
Heat
When a substance evaporates (changes physical state from a liquid to a gas) the surface of the liquid that remains behind cools down.
Evaporative Cooling
Evaporative cooling occurs because the molecules with the _____ energy (hottest ones) leave.
Greatest
Explain the popular adage, “its not the heat, its the humidity”
High humidity hampers cooling by slowing the evaporation of sweat.
A liquid consisting of a uniform mixture of 2 or more substances
Solution
A dissolving agent.
Solvent
A substance that is dissolved.
Solute
A solution in which water is the solvent.
Aqueous solution
Why are blood and most other biological fluids classified as aqueous solutions?
The solvent in these fluids is water.
In liquid water a small percentage of water molecules dissociate or break apart into ____ ions and ___ ions.
Hydrogen (H+)
Hydroxide (OH-)
(H+) and (OH-) ions are very reactive and changes in their _____ can drastically affect a cells proteins and other complex molecules.
Concentration
A substance that donates (H+) to solutions is called an ___? And has a higher concentration of of (H+) than (OH-).
Acid
A substance that removes a (H+) ion from a solution is called a ____? They do this by donating a (OH-) which combines with an (H+) ion forming H2O, thus reducing the (H+) concentration.
Base
This scale is used to describe how acidic or basic a solution is. It stands for potential of hydrogen.
pH scale
The pH scale ranges from 0-14. 0 is ____ and 14 is _____
0 is most acidic
14 is most basic
Each pH unit represents a ___ fold change in concentration of (H+) in a solution.
10 fold.
Pure water and aqueous solutions that are neither basic nor acidic are said to be____ and have a pH balance of ___?
Neutral, 7
Compred to a basic solution at pH 9, the same volume of an acidic solution at a pH 4 has ___ times for (H+).
100,000
This is the main product of fossil fuel.
Carbon dioxide.
CO2 dissolving in seawater lowers the pH of the ocean. This is called?
Ocean acidification
Why is the presence of water important in the search for extraterrestrial life?
Water plays important roles in life as we know it from moderating temperature on the same planets to functioning as the solvent of life.
