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69 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What percentage of the 92 naturally occurring elements are essential to life? |
20-25% |
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What elements make up 96% of living matter? |
Carbon
Hydrogen
Oxygen
Nitrogen |
There are 4 |
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What elements make up about 4% of living matter? |
Calcium
Phosphorus
Potassium
Sulfur |
There are 4 |
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What is the name for elements that organisms only require in minute amounts? |
Trace elements |
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What 3 subatomic particles are atoms made of? |
Neutrons (no charge) Protons (+ charge) Electrons (- charge) |
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What forms the nucleus of an atom? |
Neutrons and Protons |
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What forms a cloud around the nucleus? |
Electrons |
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What measures the near identical mass of Neutrons and Protons? |
Daltons |
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What does an atomic number represent? |
The number of Protons. |
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What does the atomic mass number represent? |
The (number) of Protons plus Neutrons. |
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An atoms total mass can be approximated by: |
The mass number |
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Who discovered atomic number in 1913 and what instrument did he use? |
Harry Moseley used an x-ray spectrograph. |
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Do all atoms of the same element have the same number of Protons? |
Yes. |
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What is an isotope? |
An atom of an element that differs in the number of Neutrons. |
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What spontaneously decays giving of particles of energy? |
Radioactive isotopes. |
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What do bio researchers use isotopes for? |
Date fossils. Trace atoms through metabolic processes. Diagnose medical disorders. |
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What is the best temperature for DNA synthesis? |
Body temperature. |
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What are valence electrons? |
They are the electrons in the outermost shell or valence shell that determine the chemical behavior of an atom. They are responsible for forming bonds between atoms. |
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What happens when an atom has a full valence shell? |
It is chemical inert (stable). |
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What is a covalent bond? |
The sharing of valence electrons by two atoms. |
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In a covalent bond are the shared electrons in both atoms valence shells? |
Yes. |
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What is a molecule? |
A molecule consists of two or more atoms held together by covalent bonds. |
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What is a single (covalent) bond? |
The sharing of one pair of valence electrons. |
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What is a double (covalent) bond? |
The sharing of two pairs of valence electrons. |
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What is electronegativity? |
An atoms attraction for the electrons in a covalent bond. The more electronegativity an atom has the stronger is pulls electrons towards it. |
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What does the term delta mean in relation to charge? |
It is a partial charge. |
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What is an ionic bond? |
Atoms sometimes strip electrons from their bonding partners. After the transfer of an electron both atoms have charges. A charged atom is called an ion. |
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What is a hydrogen bond? |
A hydrogen bond occurs when a hydrogen atom that is covalently bonded to an electronegative atom is attracted to another electronegative atom. It is a bond between partial (delta) charges. It is a weaker bond. |
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What are Van derived Waals interactions? |
They are the weakest type of bond. It is the attraction of electrons in one atom to the nucleus of another atom. |
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What do molecular shape and arrangement effect? |
The way molecules recognize and interact with each other. |
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What is a peptide? |
A chain of amino acids. |
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What do endorphins do? |
Block pain. |
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What are chemical reactions? |
The making and breaking of chemical bonds. |
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What are the starting molecules of a chemical reaction? |
Reactants. |
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What are the final molecules of a chemical reaction? |
Products. |
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The water molecule is a polar molecule. What does that mean? |
The opposite ends have opposite charges. This allows them to form hydrogen bonds with each other. |
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What is it called when hydrogen atoms hold water molecules together? |
Cohesion. |
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What is adhesion? |
An attraction between water molecules and another substance. |
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What is surface tension? |
The measure of how hard it is to break the surface of a liquid. It is related to cohesion. |
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What is specific heat? |
The amount of heat that needs to be absorbed or lost for 1 gram of any substance to change its temperature by 1°C. |
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What is the specific heat of water? |
1 calorie/gram/°C |
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What does 1 kilo calorie equal in calories? |
1000. |
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What is a joule? |
A joule is a unit of energy where 1J=0.239 Cal and 1 cal=4.184 J |
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What is one way water absorbs and releases heat? |
When hydrogen bonds are broken and formed. |
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What does the high specific heat of water accomplish? |
It minimizes temperature fluctuations to within limits that permit life. |
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What is evaporation? |
The transformation of a substance from liquid to gas. |
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What is heat vaporization? |
The heat a liquid must absorb for 1 gram to be converted to gas. |
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What is evaporative cooling? |
As a liquid evaporates, its remaining surface cools. This helps to stabilize temperatures in organisms. |
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Why does ice float? |
Because the hydrogen bonds are more "ordered" which makes ice less dense. |
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At what temperature does water reach its greatest density? |
4°C |
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What would happen if ice sank instead of floating? |
Life on Earth as we know it would be impossible. |
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What is a solution? |
A liquid that is a homogeneous mixture of substances. |
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What is a solvent? |
The dissolving agent of a solution. |
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What is an aqueous solution? |
A solution in which water is the solvent. |
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When does a hydration shell occur? |
When an ionic compound is dissolved in water. |
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Why is water a versatile solvent? |
Because of its polarity. |
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What are hydrophilic and hydrophobic substances? |
Hydrophilic: has an affinity for water. Hydrophobic: does not have an affinity for water |
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What is molecular mass? |
The sum off the masses of all the atoms in that molecule. |
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How are numbers of molecules usually measured? |
In moles. 1 mole=6.02×10^23 molecules |
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What is Avogadro's number and how many daltons equal 1 gram? |
6.02×10^23
That is how many daltons equal 1 gram.
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What is molarity? |
The number of moles of solute per liter of solution. |
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A hydrogen atom in a hydrogen bond between two water molecules can shift from one to the other. How is this done? |
The hydrogen atom leaves its electron behind and is transferred as a proton or hydrogen ion (H+). The molecule that lost the proton is now a hydroxide ion (OH-) The molecule with the extra proton is now a hydronium ion (H3O+) though it is often represented as H+. |
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What are concentrations of OH- and H+ equal in? |
Pure water. |
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What is a way to modify the concentrations of OH- and H+? |
Adding solutes known as acids and bases. |
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What do acids and bases do? |
An acid increases the H+ concentration of a solution. A base reduces the H+ concentration of a solution. |
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What are the pH values of acidic and basic solutions? |
Acidic=less than 7 Basic=greater than 7 |
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What is the pH range of most biological fluids? |
6-8 |
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What is the internal pH of most living things? |
It must remain close to 7. |
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What are buffers and what do they consist of? |
A buffer is a substance the minimizes the concentrations of H+ and OH- in a solution. Most buffers consist of a weak acid and its corresponding base which combine reversibly with H+ ions. |
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