AP Bio Midterm - Chapter 2
Terms
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- Anything that takes up space and has mass.
- Matter
- A substance that cannot be broken down to other substances by chemical reactions - each have a symbol
- Element
- A substance consisting of two or more elements combined in a fixed ratio - has characteristics beyond those of its combined elements - emergence of novel properties
- Compund
- Those required by an organism in only minute quantities - ex. Iron (FE) - some needed for all life; some needed for certain species
- Trace Elements
- Smallest unit of matter that still retains the properties of an element
- Atom
- A particle having no electrical charge found in the nucleus of an atom
- Neutron
- A subatomic particle with a single positive electrical charge, found in the nucleus of an atom
- Proton
- A subatomic particle witha single negative charge; one or more may move around the nucleus of an atom
- Electron
- An atom's central core, containing protons and neutrons
- Atomic Nucleus
- Atomic mass unit - Neutrons and protons have 1 amu
- Dalton
- Tells us the number of protons and electrons in an eletrically neutral atom.
- Atomic Number
- Sum of protons plus neutrons in the nucleus of an atom
- Mass number
- Approximation of the total mass of an atom
- Atomic Weight
- One of several atomic forms of an element, each containing a different number of neutrons and thus differing in atomic mass.
- Isotopes
- The nucleus decays spontaneously, giving off particles and energy; when changing the number of protons, it transforms the atom to a different element
- Radioactive Isotope
- The ability to do work
- Energy
- Energy that matter stores because of its position or location
- Potential Energy
- Different states of potential energy that electrons have in an atom
- Energy levels (electron shells)
- Electrons in the outermost electron shell; atom's reactivity is dependent on this
- Valence electrons
- Outermost electron shell
- Valence shell
- Three-dimensional space where an electron is found 90% of the time - specific number of orbitals of specific shapes - no more than 2 electrons can occupy the same one
- Orbial
- Attractions that let atoms stay close together
- Chemical bonds
- The sharing of a pair of valence electrons by two atoms - strongs bonds in aqueous solution - # of pairs = strength of bond
- Covalent bond
- Two or more atoms held together by covalent bonds
- Molecule
- A type of molecular notation in which the constituent atoms are joined by lines representing of their atoms
- Structural formula
- A type of molecular notation indicating only the quantity of the constituent atoms
- Molecular formula
- Two joined covalent bonds
- Double covalent bond
- The bonding capacity - equals the number of unpaired electrons in the atom's outermost shell
- Valence
- The attraction of an atom for the electrons of a covalent bond - the more it is, the more strongly it pulls shared electrons toward itself
- Electronegativity
- Electrons are shared equally
- Nonpolar covalent bond
- One atom is bonded to a more electronegative atom, the electrons of the bond will not be shared equall, creates partial charges within the molecule
- Polar covalent bond
- Weak in aqueous solution - creates ions of opposite charge, salts
- Ionic bonds
- Charged atom or molecule
- Ion
- Positively charged atom or molecule
- Cation
- Negatively charged atom or molecule
- Anion
- Compounds formed by ionic bonds
- Ionic compounds (salts)
- Forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom - helps hold DNA strands together
- Hydrogen bonds
- Weak and occur only when atoms and molecules are very close together - ever-changing "hot spots" of positive and negative charge that enable all atoms and molecules to stick to one another
- Van der Walls Interactions
- Starting materials of a chemical reaction - only rearrange matter
- Reactants
- Result of the reactants of a chemical reaction - the same number of atoms on both sides (Law of Conservation of Matter)
- Products
- 6CO2 + 6H2O = C6H12O6 + 6O2
- Photosynthesis
- The point at which the reactions offset one another exactly - their concentrations have stabilized, reactions are still going on; Rate of forward reaction = Rate of reverse
- Chemical equilibrium