exam 1 (ch2/ch3)

CHEMISTRY

Science that deals with the structure of matter

Matter

Anything that takes up space and has mass

Mass

the amount of material in matter

Weight

the force of gravity exerted on the object

Atom

The smallest units of matter

Subatomic Particles

protons, neutrons, and electron

Proton

positive charge

Neutron

neutral charge

Electron

negative charge

Atomic Number

number of protons

Mass Number

Total number of neutrons and protons in an atom

Electron Cloud

contains electrons

Electron Shell (energy level)

2D representation of a electron cloud

Valence Shell

outermost shell of any atom

Elements (Periodic Table)

pure substance composed of atoms of one

kind

Principle Elements of the human body

Carbon, Oxygen, Hydrogen, Nitrogen

Isotope

versions of elements based on mass number

Atomic Weight (amu or Dalton)

Average of the different atomic masses and proportions

of different isotopes

CHEMICAL BONDS

form molecules and compounds

Molecules

Two or more atoms joined by strong bonds

Compounds

Two or more atoms of different elements

joined by strong or weak bonds

Molecular Weight

the sum of the atomic weights of atoms from molecules or compounds

Ionic Bonds

One atom gives an electron to another atom

Ions

an atom or group of atoms that has an electric charge

Cation

Ions with a positive charge

Anion

Ions with a negative charge

Covalent Bonds

sharing electrons with another atom

Electron Pairs

two electrons that share a molecular orbital and have opposite spins

Single

sharing one pair of electrons from each atom

Nonpolar Covalent Bonds

Equal sharing of electrons between atoms that have equal pull on the electrons

Polar Covalent Bonds

Unequal sharing of electrons because one atom has a disproportionately strong pull on the electrons

Polarity

One side is more positive than the other

three types of rna

mRNA, rRNA, tRNA

mRNA

carries genetic information to the DNA from the nucleus to the cytoplasm for protein synthesis

rRNA

makes up ribosomes with other proteins

tRNA

transfers amino acids to the ribosomes