Glossary of ch 2 - atoms, molecules, and ions
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- what are the main subatomic particles of atoms?
- protons (+ charge), neutrons (neutral), electrons (- charge)
protons and neutrons are located in the nucleus (nucleus diameter is approx 10**-13 cm)
electrons move around the nucleus, avg distance 10**-8 cm from the center
- what is the charge for protons? electrons?
- postive charged protons: +1.602 x 10**-19 C
negative charged electrons: -1.602 x 10**-19 C
- what is atomic number?
- the number of protons and electrons in an atom (if not equal they are ions)
chemical property of the atom is determined by the number of electrons
note: the number of neutrons can vary which gives rise to isotopes
- what is atomic mass?
- atomic mass = number of protons + number of neutrons, e.g.
13 (atomic mass)
6 (atomic number)
--> 6 protons, 6 electrons, 7 neutrons
- what is a molecule?
- molecule: the assembly of two or more atoms
the atoms are held together by chemical bonds
molecules have a molecular formula
- molecular mass?
- the sum of the atomic mass for all atoms in a molecule
e.g. H2O; 1 + 1 + 16 amu (atomic mass units)
- what are ions? charge?
- cation: + charged ion, formed when one or more electrons is lost
anion: - charged ion, formed when one or more electrons is added
charge = atomic number - number of electrons
- what are polyatomic ions?
- polyatomic ions are composed of several cation and anion atoms.
e.g. two Br- anions are combined with one Ca2+ cation to form CaBr2
- what is a structural formula?
- shows the arrangement of the atoms in a molecular formula, e.g. water:
- What are acids?
- Acids generate H+ cation and an anion when dissolved in water.
e.g. H2S + H20 -> H+ + HS-
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