Chapter 2 Flashcards
Chemistry Comes Alive
Energy
The capacity to do work
-potential: inactive/ stored
-kinetic: energy of motion
Forms of energy
A. Chemical: making/ breaking of chemical bonds
B. Electrical: movement of charged particles
C. Mechanical: movement of matter
D. Radiant: light, other electromagnetic radiation
Matter
- All living things consist of matter
A. matter is anything that occupies space/ has mass. - liquid, solid, or gas
Mass
Actual amount of matter an object contains
Weight
Measure of force of gravity on an object
Element
A. A substance that cannot be made into a simpler substance by ordinary chem. reactions
B. Composed of specific types of atoms
C. There are (at least) 112 elements
- 92 (nature)
- 24 (naturally in the body)
Most common: H,C,O,N
Protons
- found in the nucleus
- positively charged
Neutrons
- found in the nucleus
- neutral charge
Electrons
- orbit around the nucleus
- negatively charged
What makes an atom neutral?
of protons=# of electrons
What determines an element?
A. Number of protons
B. The # of protons in the nucleus is the elements atomic number
Isotopes
- atoms have same # of protons, different # of neutrons
- same chemical characteristics
- mass #: indicates the # of protons, and neutrons
Radioactive Isotopes
- unstable, and decay into other isotopes
- even into other elements
Molecule
A. 2 or more atoms held together by chemical bonds
- could be the same element
Compound
A. Molecules composed of 2 or more different elements
Mixtures
A. substances composed of 2 or more components physically mixed
Solutions
A. Mixture of 2 or more components
-ex: salt water and blood plasma
Solvent (Solution)
A. The medium in which the other matter mixed
Solute (Solution)
A. The various other components in the mixture.
Homogenous
A. mixture that has a uniform composition throughout
- components are evenly distributed and cannot be easily separated
Concentration
A. Measure of the amount of solute dissolved in a solvent
- Milligrams/ deciliter (mg/dl)
- Molarity (M)- moles/ liter
Mixtures
A. Colloid
- Heterogenous mixtures that appear milky/ translucent (Jell-O)
- Smaller particles which scatter light.
- May undergo sol-gel transformations
Suspensions (mixture)
A. Blood
- red blood cells suspended in plasma
- heterogenous mixture with larger, often visible particles.
Chemical Bonds
Strongest to weakest
A. Covalent
B. Ionic
C. Hydrogen
D. van der walls= hydrophobic
Role of electrons
A. They form clouds called shells.
- each shell: 1 or more orbitals
-first 3: hold 2, 8, and 18
B. Outer shell is the valence shell
When are atoms stable?
A. Valence shell is filled with electrons
- Atoms are chemically reactive if the valence shell is not full of electrons
Covalent Bond
A. Electrons shared among 2 or more atoms
B. Carbon + 4 Hydrogen=Methane
- carbon: 4 valence electrons to share
- hydrogen: 1 valence electron to share
Single, double, triple
A. Refers to the # of atoms shared
Polar (Covalent bond)
A. Electrons are shared unequally
Non-Polar (Covalent Bond)
A. Electrons are shared equally
- CO2 has 2 non-polar covalent bonds
Ionic Bonds
A. Electrons can be completely separated, transferred from one atom to another.
- forms + and - ions.
B. Oppositely charged ions attract each other
Cation
A. Electron donors
B. Positive charge
Anion
A. Electron acceptors
B. Negative charger
Hydrogen Bonds
A. Weakest attractions btwn diff. molecules.
- contain polar covalent bonds
- covalently bound H attracts charged atoms
Water
A. Forms many H-bonds.
B. Surface tension
Chemical Reactions
A. Formation, rearrangement, breakage of chem. bonds
- energy is transferred. waste heat is lost.
Chemical Equations
A. written in the form of the chemical reactions involved
- A+B—>C
-Reactants=A,B
-Products=C
Synthesis (Anabolic) Reactions
A. Atoms/ molecules combine to form larger, more complex molecules
- ALWAYS involves some type of chem. bond formation
-ALWAYS involves the input of chem. energy
-A+B—> AB
- Amino Acids—> Protein
Decomposition (Catabolic) Reactions
A. Large molecule is broken down into smaller molecules, constituent atoms.
- chem. bonds broken
- chem. energy is always released.
-that energy may or may not be useful for another purchase
- D—> E+E+E+E…+E
Chem. Exchange Reactions
A. Both synthesis and decomp. occur in the same reaction
- AB+CD<—>AD+CB
Reversibility of chem. reactions
A. All chem. reactions are theoretically reversible.
- energy has to be added back to reverse
What do chem. reactions push for?
A. State of equilibrium
- rates of forward/ reverse reactions are =
- products/ reactants are in balanced proportions
Things that change rate of reactions
A. Molecular collisions required for a chem. reaction
-Probability is impacted by:
1. Temperature
2. Particle Size
3. Concentration
4. Catalysts
Inorganic Compounds
A. Usually lack carbon atoms
- usu. smaller molecules
- H2O
- Gases, e.g., O2, CO2, N2
- Various ions: electrolytes
Waters Special Properties
- High Heat capacity
- High heat of vaporization
- Polarity Properties (is a good solvent)
- Reactivity
- Lubrication/ Cushioning
Salts
A. Contains cations and anions
B. Ionize into component ions when dissolved in H2O
C. Ions called electrolytes
Acids
A. Break ionic bonds when dissolved in H2O, changes # of ions in solution.
B. Proton donors, dissociate to release hydrogen ions/ anions
Bases
A. Break ionic bonds when dissolved in H2O, changes # of ions in solution.
B. Proton acceptors
C. Generally dissociates into Hydroxyl ion and one/ more cations
