Introduction to Chemistry:
Matter and its Interactions
Mr. Pierson
Fall 2013
Atoms
• Consist of protons, neutrons, and electrons
• Protons – positively charged subatomic particle found in the nucleus
• Electrons – negatively charged subatomic particle outside of the nucleus
• Neutrons – neutrally charged (no charge) subatomic particle found in the
nucleus
The Periodic Table
• Elements – simplest forms of matter that can exist under normal
laboratory conditions.
• Matter – anything that takes up space and has mass.
• Mass – the amount of matter that an object contains.
• The periodic table orders elements horizontally by the number of
protons in the atom’s nucleus and places those with similar chemical
properties in columns.
• Chemical property – the ability of a substance to undergo chemical reactions
and to form new substances.
Important Things to Learn Right Away
• Symbols of Common Elements
• Symbols of Common Polyatomic Ions
• The Periodic Table
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Alkali metals
Alkaline earth metals
Nonmetals
Noble gases
The Alkali Metals
• Li
• Na
•K
• Rb
• Cs
• Fr
Alkaline Earth Metals
• Be
• Mg
• Ca
• Sr
• Ba
• Ra
Nonmetals
•B
• C, Si
• N, P, As
• O, S, Se, Te
• F, Cl, Br, I, At
Noble Gases
• He
• Ne
• Ar
• Kr
• Xe
• Rn
Metals, Nonmetals, Metalloids
• Metals – elements that have a high electrical conductivity and a high
luster when clean.
• Nonmetals – elements that are nonlustrous and are generally poor
conductors of electricity.
• Example: Argon, Chlorine (gases); Carbon, Sulfur (solids); Bromine (liquid at
room temp.)
• Metalloids – elements with the properties of both metals and
nonmetals.
• Example: Silicon and Germanium
Assignment
• Pg. 109, “Concept Practice” #1
• Pg. 136, “Practice Questions and Problems” #32
• Pg. 137, “Mastery Questions and Problems” #54
• List the symbol and names of the Alkali Metals, Alkaline Earth Metals,
Nonmetals, and Noble Gases
Atoms and Ions
• Ions- atoms or groups of atoms that have a positive or negative
charge.
• Cations – any atom or group of atoms with a positive charge
• Has less electrons than protons
• Example: Na+
• Has 11 protons and only 10 electrons when it loses an electron (with 1 more proton only
the “+” is used, if 2 more protons than electrons we would write “2+” to represent that
there are 2 more protons than electrons)
• Anions – atoms or groups of atoms with a negative charge
• Has more electrons than protons
• Example: Cl• Has 17 protons and 18 electrons when chlorine gains an electron. Remember, electrons
are negatively charged, so in this case we have 18 negatives and 17 positives for an
overall -1 (17-18).
Compounds
• Molecule – an electrically neutral group of atoms that act as a unit.
• Example: H2O
• Water is a molecular compound – compounds that are composed of
molecules
• Ionic Compound – composed of positive cations and negative anions.
• Example: NaCl
• Chemical formula – shows the number and kinds of atoms in the
smallest representative unit of the substance.
• Molecular formula – shows the number and kinds of atoms present
in a molecule of a compound.
Compounds, cont.
• Chemical compound (compound = 2 or more things combined)
• Molecular (2 or more molecules)
• Ionic (2 or more ions)
• All different compounds have different properties
• Must use chemical formula (remember, a chemical symbol is the same thing as an element
symbol, i.e. H, He, etc.)
• If the chemical is a molecular compound, then a molecular formula is used
• Example: H2O
Formula Units
• = the lowest whole-number ratio of ions in an ionic compound.
• Example: Sodium Chloride
• Na+ needs 1 electron and Cl- has 1 extra electron, the ratio is 1:1, thus the formula unit is
NaCl.
• Mg2+ needs 2 electrons and Cl- has 1 extra electron, so it would take 2 Cl- anions to
combine with the Mg2+ cation, thus the ratio is 1:2 and the formula unit = MgCl2
• What would the formula unit be for Li+ and S2- ions?
In-Class Assignment
• Read pg. 116 – 123
• Copy Table 5.4 “Common Polyatomic Ions” into your notes.