Chemistry
The science of change: structure of atoms, basic chemical building blocks, atoms combine to form increasingly complex structures
Matter
Made up of atoms; atoms join together to form chemicals with different characteristics; chemical characteristics determine physiology at the molecular and cellular levels
Atoms
Building blocks of matter
Subatomic particles
protons, neutrons, electrons
Proton
Positive charge, 1 mass unit
Neutron
Neutral, 1 mass unit
Electron
Negative charge, low mass
Atomic structure
atomic number, nucleus, electron cloud
Atomic number
Number of protons
Nucleus
Contains protons and neutrons
Electron cloud
Contains electrons
Hydrogen-1
A typical hydrogen nucleus contains a proton and no neutrons, mass number:1
Hydrogen-2, deuterium
Nucleus contains a proton and a neutron, mass number: 2
Hydrogen-3, tritium
Nucleus contains a proton and two neutrons, mass number: 2
Oxygen, O (65)
A component of water and other compounds; gaseous form is essential for respiration
Carbon, C (18.6)
Found in all organic molecules
Hydrogen, H (9.7)
A component of water and most other compounds in the body
Nitrogen, N (3.2)
Found in proteins, nucleic acids, and other organic compounds
Calcium, Ca (1.8)
Found in bones and teeth; important for membrane function, nerve impulses, muscle contraction, and blood clotting
Elements
Determined by atomic number of an atom; most basic chemicals
Isotopes
Specific version of an element based on its mass number
Mass number
Number of proton plus the number of neutrons
Why only are the number of neutrons different?
Because the number of protons determines the elements
Atomic weight
Exact mass of all particles; measured in moles; average of the mass numbers of the isotopes
Electrons in the electron cloud
Determine the reactivity of an atom
Electron cloud
Contains shells, or energy levels, that hold a maximum number of electrons
Valence shell
Outermost shell that determines bonding
Chemical bonds
Involve the sharing, gaining, and losing of electrons in the valence shell; form molecules and/or compounds
Three types of chemical bonds
Ionic, covalent, hydrogen
Ionic bonds
Attraction between cations (electron donor) and anions (electron acceptor) then draws the two ions together
Covalent bonds
Strong electron bonds involving shared electrons
Hydrogen bonds
Weak polar bonds based on partial electrical attractions; bonds between adjacent molecules, not atoms, slightly positive and negative portions of polar molecules being attracted to one another
Molecules
Two or more atoms joined by strong bonds
Compounds
Two or more atoms OF DIFFERENT ELEMENTS joined by strong or weak bonds
Explain: H2= Molecule only, H2O= molecule and compound
Compounds are all molecules, but not all molecules are compounds
Electron donor
Loses one or more electrons and becomes a cation, with a positive charge
Electron acceptor
Gains those same electrons from the donor and becomes an anion, with a negative charge
Ion
A subscript plus or minus sign following the symbol of an element
Single covalent bond
Sharing one pair of electrons
Double covalent bond
Sharing two pairs of electrons
Triple covalent bond
Sharing three pairs of electrons
Nonpolar covalent bonds
Involve equal sharing of electrons because atoms involved in the bond have equal pull for the electrons
Polar covalent bonds
Involve unequal sharing of electrons because one of the atoms involved in the bond has a disproportionately strong pull on the electrons; ex: water
Hydrogen bonds between H2O molecules causes
Surface tension
Chemical reaction
Either new bonds are formed or existing bonds are broken; reactants, products, metabolism; in cells, cannot start without help
Reactants
Materials going into a reaction
Products
Materials coming out of a reaction
Metabolism
All of the reactions that are occurring at one time
Energy
Power to do work
Studied by 52 People
