Chemistry Ch 2

• The periodic table shows the propoerties of various elements.
• Sodium = Na
• Potassium = K
• Iron = Fe
• Copper = Cu
• Silver = Ag
• Tin = Sn
• Antimony = Sb
• Tungsten = W
• Gold = Au
• Mercury = Hg
• Lead = Pb
• Each corner of the atomic symbol have specific uses: top left is the atomic mass, top right is the charge, bottome left is the atomic number, and the bottom right is the subscript.
• # of electrons in an ion = Z - charge of ion
• # of neutrons= A - Z
• Subatomic particles include positron, electron/beta, alpha, proton, and neutron
• Radioactivity is a property of matter whereby an unstable nucleas spontaneously emits small particles of energy in order to become more stable.
• Radioactive decay is the process of how an unstable nucleus becomes a stable state.
• An isotope that contians an unstable nucleus is a radioactive isotope or radioisotope.
• During radioactive decay, subatomic particles are emitted which changes the nuclear mass and nuclear charge. This results in a completely different element.
• Energy may also be released as gamma rays.
• Mass spectrometry allowed scientists to calculate the charge to mass ratio of ions.
• The mass spectrum is the pattern of charge-to-mass ratios and the intesity of each ratio.
• Weighted average= sum of (mass of isotope)(abundance of isotope)
• The lanthanide and actinide series are placed below the periodic table.
• Groups of elements include alkali metals, alkaline earth metals, transition elements, halogens, and noble gases.
• Chemical reactions occur when one atom collides with another. The outermost electrons make the first contact, which is why elements with similar electronic sutrcutres have similar chemical properties.
• A differentiating electron is the electron in a neutral element that makes it different from the previous element.
• An example of a differentiating electron for noble gases is that all noble gases have completely filled s and p sublevels.
• Isoelectronic refers to atoms and ions that have identical electron configurations.
• Mercury and bromine are liquid elements under normal conditions.
• Noble gases include hydrogen, nitrogen, oxygen, fluorine and chlorine, which are all gases under normal conditions.
• Metalloids exhibit properties of both metals and nonmetals.
• An element may have two or more distinct sets of chemical and physical propoerties. For example, oxygen and ozone are allotropes of oxygen.
• The melting and boiling points of metals tend to decrease going down the periodic table.
• The melting and boiling points of nonmetals increase going down the periodic table.
• The atomic radius increases down a group because of an increase in energy levels.
• The atomic radius decreases across a period because of an increase in the strong nuclear force (due to increasing atomic number)
• Core electrons shield outer electrons from the strong nuclear charge. However, valence electrons do not shield other valence electrons from the remaining nuclear charge.
• The effective nuclear charge regards how the strong nuclear force acts upon core and valence electrons.