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anything that occupies space and has mass
The amount of matter in an object
the gravitational force acting on an object of a given mass
simplest type of matter with unique chemical properties; composed of atoms of only one kind
smallest particle of an element that has chemical characteristics of that element
- Neutrons: no electrical charge
- Protons: one positive charge
- Electrons: one negative charge
formed by protons and neutrons
most of the volume of an atom occupied by electrons
equal to number of protons in each atom, which is equal to the number of electrons
number of protons plus number of neutrons
- 2 or more forms of same element with same number of protons and electrons but different neutron number.
- for example: 3 types of hydrogen
- Isotopes have same atomic number but different mass numbers
average mass of naturally occurring isotopes
- •Forms of atoms that emit radioactivity such as gamma rays, which can then be measured
- •Used clinically and in research
- •Examples of uses:
- –Tracking hormone uptake
- –Treating cancer
- –Sterilization of materials to be used in surgery
Electons and Chemical bonding
Intramolecular bonding occurs when outermost electrons are either shared with or transferred to another atom.
- Ionic bonding: atoms exchange electrons
- Covalent bonding: 2 or more atoms share electron pairs
- an atom loses or gains electrons and becomes charged
- cation: positively charged ion
- anion: negatively charge ion
In an ionic bond, cations and anions are attracted to eachother and remain close to each other
Covalent bonds - single, double, nonpolar, polar
- Atoms share one or more pairs of electrons.
- The resulting combination of atoms is called a molecule.
- single covalent: 2 atoms share 1 pair of electrons
- double covalent: 2 atoms share 4 electons
- nonpolar covalent: electrons shared equally because nuclei attract the electrons equally
- polar covalent: electrons not shared equally because 1 nucleus attracts the electrons more than the other does
2 or more atoms chemically combine to form an independent unit
–Example: a hydrogen molecule (H2)
- a substance composed of 2 or more different types of atoms chemically combined.
- -example: water (H2O)
determined by adding up atomic masses of its atoms and ions
-example: NaCl (22.99 + 35.45)
- -forces between molecules
- -result from weak electrostatic attractions between oppositely charged parts or molecule, or between ions and molecules
- -weaker than forces producing chemical bonding
- -include hydrogen bonds and the properties of solubility and dissociation
- occur when the positively charged hydrogen of one molecule is attracted to the negatively charged oxygen, nitrogen, or fluorine of another molecule
- –For example, in water the positively charged hydrogen atoms of one water molecule bond with the negatively charged oxygen atoms of other water molecules
- –Hydrogen bonds play an important role in determining the shape of complex molecules
Solubility & Dissociation
- Solubility: Ability of one substance to dissolve in another
- -example: sugar or salt dissolves in water
- Dissociation (separation): occurs when ionic compounds dissolve in water, their ions separate from one another because the cations are attracted to the negative ends of the water molecules, and the anions are attracted to the positive ends of water molecules
Electrolytes & Nonelectrolytes
- Electrolytes: solutions made by the dissociation of cations and anions in water
- -have the capacity to conduct an electric current
- -currents can be detected by electrodes
- Nonelectrolytes: solutions made by molecules that dissolve in water, but do not dissociate; do not conduct electricity. i.e. pure water
atoms, ions, molecules or compounds interact to form or break chemical bonds
- reactants: substances that enter into a chemical reaction
- products: substances that result from the reaction
Chemical bonds are made (synthesis; anabolism) and are broken (decomposition; catabolism) during chemical reactions
collective term used for the sum of all of the anabolic and catabolic reaction in the body
- 2 or more reactants chemically combine to form a new and larger product. Anabolism
- -chemical bonds made; energy stored in bonds
- -responsible for growth, maintenance and repair
- -Dehydration: synthetic reaction where water is a product
- -produce chemicals characteristic of life: carbohydrates, proteins, lipids, and nucleic acids
- A large reactant is broken down to form smaller products. Catabolism.
- -chemical bonds broken; energy released
- -Hydrolysis: water is split into 2 parts that contribute to the formation of the products
- -example: the breakdown of ATP to form ADP and inorganic phosphate with a simultaneous release of free energy
Reversible reactions & Equilibrium
- Reversible reaction: chemical reactions in which the reaction can proceed either from reactants to products or from products to reactants.
- Equilibrium: rate of product formation is equal to rate of reactant formation
Analogy: trough containing water, divided into 2 compartments by a partition, but the partition contains holes that allow water to move freely between the compartments. Because water can move in ether direction, this is like a reversible reaction.
- O-R reactions: the complete or partial loss of an electron by oe substance is accompanied by the gain of that electron by another substance
- -synthetic/decomposition reaction can be oxidation-reduction reactions
- -reactions can be described in more than one way
- Oxidation:loss of an electron by a substance
- Reduction:gain of an electron by a substance
the capacity to do work (to move matter)
- Potential energy: energy stored in chemical bonds; energy that could do work if were released. Breaking chemical bonds releases energy
- Kinetic energy: does work and moves matter
- Mechanical energy: energy resulting from the position or movement of objects
- Chemical energy: form of potential energy in the chemical bonds of a substance
- Heat energy: energy that flows between objects of different temperatures
- When a chemical bond is broken and energy is released, only some of the energy is used to manufacture ATP.
- -energy that is released but not captured is released as heat
- -heat is used by mammals to maintain body temperature
Speed of chemical reactions
- Temperature affects rate of reaction
- -increase in temperature means increase of kinetic energy
- -molecules move faster, collide harder and more frequently
- Concentration of reactants.
- -as concentration of reactants increases, rate of reaction increases.
- -a decrease in O2 cells can cause death as rate of aerobic chemical reactions decreases.
substances that increase the rate of chemical reactions without being permanently changed or depleted
Enzymes & Activation Energy
- Activation energy: minimum energy reactants must have to start a chemical reaction
- Enzymes: proteinaceous catalysts that increase the rate of chemical reactions by lowering the activation energy necessary for reaction to begin.
Activation energy and enzymes
Inorganic & Organic chemistry
- Inorganic chemistry: generally substances that do not contain carbon (lack of carbon-hydrogen bonds)
- -water, oxygen, calcium phosphate, metal ions (magnese, magnesium, zinc, copper)
- -exeptions: CO (Carbon monoxide), CO2 (Carbon dioxide) , and HCO3- (bicarbonate ions)
- Organic Chemistry: study of carbon-containing substances. Those that are biologically active are called biochemicals
cohesion and adhesion
- Water: molecule composed of 1 atom of oxygen joined to 2 atoms of hydrogen by covalent bonds.
- Cohesion: attraction of water to another water molecule
- Adhesion: same attractive force of hydrogen bonds with water will also attract other molecules.
- - combination of cohesion and adhesion helps hold cells together and move fluids through the body
- High specific heat: large amount of heat require to raise temperature of water
- -stabilizes body temperature
- -lubricant, cushion (serous membranes around organs)
- Participates in chemical reaction many reactions take place in water (dehydration & hydrolysis)
- Serves as a mixing medium
Mixture (suspension & colloid)
Solution (Solvent, solute)
- Mixture: substances physically but not chemically combined
- -suspension: materials separate unless stirred. Sand and water
- -Colloid: dispersal of tiny particles through a medium. Milk
- Solution: mixture of liquids, gasses, or solids that are uniformly distributed and chemically combined (no clear boundary between them)
- solvent: that which dissolves the solute
- solute: that which dissolves in the solvent
- blood is a mixture, solution (gases in blood), and colloid.
- Concentration: measure of particles of solute per volume of solution
- Osmolality: reflects the number of particles (not type) dissolved in one kilogram of water
- -concentration of body fluids influences movement of fluid into and out of cells
Acids and bases; salts and buffers
- Acid: proton donor or any substance that releases hydrogen ions
- Base: a proton acceptor or any substance that binds to or accepts hydrogen ions
- Salt: a compound consisting of a cation other than a hydrogen ion and an anion other than a hydroxide ion
- example:NaCl (sodium chloride)
- Buffer: a solution of a conjugate acid-base pair in which acide and base components occur in similar concentrations