Ch. 2 The Chemical Basis of Life Flashcards
What is heat?
It is the energy due to movement of molecules in a body of matter. Most random form of energy.
What is an electron?
A sub-atomic particle that circles an atom’s nucleus. Has a negative charge.
Determines how atoms will behave around other atoms. The farther from the nucleus, the more energy.
What is an atom?
The smallest unit of matter that retains the properties of an element.
What is an ion?
It is a charged atom or molecule. Has gained/lost one or more electrons thus acquiring an electrical charge.
What is acid precipitation?
It is caused by pollutants that combine with water in the air. Results from sulfur oxides and nitrogen oxide (fossil fuels).
What is matter?
It is anything that occupies space and has mass. Composed of chemical elements.
What is a molecule?
Formed by two or more atoms held together by covalent bonds. Major players for living organisms in terms of communication and immunization.
What are found in the nucleus of an atom?
Neutrons and protons
What responsible for surface tension?
Cohesion
What are isotopes?
Varient forms of an element with different numbers of neutrons.
What is cohesion?
The tendency of water molecules to stick together. It is an attraction between molecules of the same kind.
What is a neutron?
A sub-atomic particle with no electrical charge.
What is temperature?
It measures the intensity of heat.
In this bond the electrons are shared unequally.
Polar covalent bond
How many natural occurring elements are there?
92
What is a compound?
It contains two or more elements in a fixed ratio. Common. Nature usually has 2 elements. Living organisms usually have 3 to 4.
What are hydrogen bonds?
Weak bonds between water molecules. Slightly positive and negative charge exists between different molecules to form a weak bond.
What is an acid?
It donates H+ ions to solutions. Increases the hydrogen ion concentration in a solution. Burns.
What is covalent bond?
A bond formed when two atoms share electrons of the outer shell.
What is a proton?
A positively charged particle from the nucleus of an atom.
What is a solvent?
The dissolving agent in a solution.
What is a solution?
A liquide containing a homogeneous mixture of substances.
What is an ionic bond?
A bond formed when two ions of opposite charges attract each other. Electrical attraction is what holds the ions together. Due to transfer of elections.
What is a solute?
The substance dissolved in a solution.
What is a base?
It accepts H+ ions and removes them from the solution. A substance that decreases the hydrogen ion concentration in a solution. Dissolves.
- Alkali
What is a chemical element?
A substance that cannot be broken down to other substances by ordinary chemical means.
How many natural elements are there? And how many are essential to life?
92 natural elements and 25 essential to life.
What elements make up 96% of the human body?
Carbon, Hydrogen, Oxygen, and Nitrogen
What is a trace element?
An element that is essential for the survival of an organism but only in minute quantities
What is the nucleus?
An atom’s core containing protons and neutrons. Electrons will orbit due to attraction.
Atomic Number
Number of protons in an atom of an element
Mass Number
The sum of the # of protons and neutrons in an atom’s nucleus
Atomic Weight
Approximate total mass of an atom
Isotope
Variant form of an atom; same # of protons but different number of neutrons. Doesn’t effect chemical properties but physical properties.
Radioactive isotope
Isotope whose nucleus decays spontaneously; giving off energy/particles
What are radioactive isotopes used for?
To trace and monitor molecules thru the chemical changes.
Electron shells
An energy level representing the distance of an electron from the nucleus of an atom.
- outermost shell determines chemical properties (full tend not to react)
What is a chemical bond?
An attraction between 2+ atoms resulting from a sharing of outer shell electrons or the presence of opposite charges on atoms. Electronegativity is the glue.
What are 3 ways to show covalent bonds?
1) Molecular
2) Electron configuration
3) Structural
What is a double bond?
Type of covalent bond with 2 atoms that share 2 pairs of electrons
Electronegativity
The tendency for an atom to pull electrons toward itself.
Non-polar covalent bond
An attraction between atoms that share 1+ pairs of electrons equally because atoms have similar electronegativity
Polar covalent bond
Attraction between atoms that share electrons unequally because atoms differ in electronegativity; partial negative, partial positive
Polar Molecule
A molecule containing a polar covalent bond
What is the key to water molecules ability to interact?
Polarity
Hydrogen Bond
Type of weak chemical bond formed when the partially positive hydrogen atom participating in a polar covalent bond in one molecule is attracted to the partially negative atom participating in a polar covalent bond in another
Surface tension
A measure of how difficult it is to stretch/break surface of liquid
pH Scale
Relative acidity of a solution (0 to 14). Measures the H+ and OH- concentration.
- potential hydrogen
Buffer
Chemical substance that resists changes in pH by accepting/donating H+ ion. Stabilizes.
Chemical reaction
A process leading to chemical changes in matter; involves making and break bonds
Reactants
Starting material of chemical reactions
Products
End result of chemical reactions
Do chemical reactions create/destroy matter?
No. Only rearranges.
What is chemistry?
The study of matter.
Electron cloud
Orbiting electrons surrounding nucleus. Stays due to attraction.
What are valance electrons?
Outermost electrons that vary in energy. The close the less energy. The father the more energy. In the first shell, 2 electrons. In the second and so forth, 8 electrons.
Why are noble gases non-reactive?
They have complete electron sets.
Period Law
Chemical properties tend to occur periodically thru out the periodic table. Columns have same # of valance electrons and properties.
3 types of chemical bonds
1) Ionic
2) Covalent
3) Hydrogen
Why does water have the properties that it does?
Polarity and hydrogen bonding.
High Heat Capacity
Large amounts of energy can be added/subtracted without affecting temperature significantly.
What are the properties of water?
1) Cohesion
2) Thermal Properties
3) High Heat of Vaporization
4) Evaporative Cooling
5) Density
6) Versatile Solvent
Hydrophobic
Doesn’t break down in water
Ionization
Formation of ions
What is the ionization of water?
H2O -> H+ + OH-
What are examples of neutral solutions?
Distilled water and bodily fluids
2 types of chemical reactions
1) Exothermic
2) Endothermic
Exothermic
External heat. Broken bonds and energy released.
Endothermic
Internal Heat. Bonds formed and energy absorbed.
