Science 1206 – Unit 2: Chemistry
Topic 2
Matter and the Periodic Table
•Chemistry - the science of matter; the branch of the natural sciences dealing with the composition of
substances and their properties and reactions
•Matter - that which has mass and occupies space
•Pure Substance - a substance that contains only one kind of molecule throughout.
•Impure Substance - a substance that contains more than one kind of molecule
•Physical Property - A characteristic of a material that can be measured without changing the material's
chemical composition, such as: color, density, melting point, or boiling point.
•Chemical Property - The way a substance reacts with other substances
•A chemical change can be indicated by:
–A color change
–Formation of a solid (precipitate)
–Formation of bubbles
–An energy change (heat or light)
•Reactants – the substances that are combined through a chemical reaction to make new substances; found on
the left side of a chemical equation.
•Products – those new substances that are made from the chemical reaction of two or more other substances
CH4 + 2O2  CO2 + H20
Reactants  Products
Chemical Tests
•Test for Hydrogen:
–Collect gas in a test tube
–Insert a lit splint in the tube
–Hydrogen will “pop”
–2H2 + O2 + Energy  2H2O
•Test for Oxygen:
–Collect gas in a test tube
–Light a flint and then blow it out
–Insert the glowing flint in the tube
–Oxygen will make it burst into flame again
–2C60H122 + 181O2  120CO2 + 122H2O + energy
•Test for Carbon Dioxide(CO2 ):
–Collect gas in a test tube
–Pour a little limewater into the test tube and shake it up
–The
limewater (calcium hydroxide solution) will turn cloudy if the gas is CO2
–Ca(OH)2 + CO2  CaCO3 + H2O
•Test for Water
–Collect colorless liquid in a test tube
–Place a piece of cobalt (II) chloride paper in the test tube.
–The cobalt (II) chloride paper will turn pink if the liquid is water.
–CoCl2 + 6 H2O  CoCl2 . 6 H2O
–
–The Periodic Table
•Periods are the rows of the periodic table
–They loosely represent energy levels of the atoms.
•Families are the columns of the periodic table they group elements with similar properties.
Families of Elements
The Alkali Metals First column of the table. They include:
Lithium
Sodium
Potassium
Rubidium
Cesium
Francium
The alkali metals, found in group 1 of the periodic table are very reactive metals that do not occur freely in
nature. These metals have only one electron in their outer shell. Therefore, they are ready to lose that one
electron in ionic bonding with other elements. As with all metals, the alkali metals are malleable, ductile, and
are good conductors of heat and electricity. The alkali metals are softer than most other metals. Cesium and
francium are the most reactive elements in this group. Alkali metals can explode if they are exposed to water.
The Alkali Earth Metals Second column of the table. They include:
Beryllium
Magnesium
Calcium
Strontium
Barium
Radium
The alkaline earth elements are metallic elements found in the second group of the periodic table. All alkaline
earth elements have an oxidation number of +2, making them very reactive. Because of their reactivity, the
alkaline earth metals are not found free in nature.
The Transition Metals 38 elements in the middle section of the table (ie groups 3 -12)
The 38 elements in groups 3 through 12 of the periodic table are called "transition metals". As with all metals,
the transition elements are both ductile and malleable, and conduct electricity and heat. The interesting thing
about transition metals is that their valence electrons, or the electrons they use to combine with other elements,
are present in more than one shell. This is the reason why they often exhibit several common oxidation states.
There are three noteworthy elements in the transition metals family. These elements are iron, cobalt, and nickel,
and they are the only elements known to produce a magnetic field.
The Noble Gases Last column of the table. They include:
Helium
Neon
Argon
Krypton
Xenon
Radon
The six noble gases are found in group 18 of the periodic table. These elements were considered to be inert
gases until the 1960's, because their oxidation number of 0 prevents the noble gases from forming compounds
readily. All noble gases have the maximum number of electrons possible in their outer shell (2 for Helium, 8 for
all others), making them stable.
The Halogens Second last column of the table. They include:
Fluorine
Chlorine
Bromine
Iodine
Astatine
The halogens are five non-metallic elements found in group 17 of the periodic table. The term "halogen" means
"salt-former" and compounds containing halogens are called "salts". All halogens have 7 electrons in their outer
shells, giving them an oxidation number of -1. The halogens exist, at room temperature, in all three states of
matter:
Solid- Iodine, Astatine
Liquid- Bromine
Gas- Fluorine, Chlorine
The Metalloids Found along the staircase that separates metals and non-metals. They include:
Boron
Silicon
Germanium
Arsenic
Antimony
Tellurium
Polonium
Metalloids are the elements found along the stair-step line that distinguishes metals from non-metals. This line
is drawn from between Boron and Aluminum to the border between Polonium and Astatine. The only exception
to this is Aluminum, which is classified under "Other Metals". Metalloids have properties of both metals and
non-metals. Some of the metalloids, such as silicon and germanium, are semi-conductors. This means that they
can carry an electrical charge under special conditions. This property makes metalloids useful in computers and
calculators
The Non-metal Elements
They include:
Hydrogen
Carbon
Nitrogen
Oxygen
Phosphorus
Sulfur
Selenium
Non-metals are the elements in groups 14-16 of the periodic table. Non-metals are not able to conduct
electricity or heat very well. As opposed to metals, non-metallic elements are very brittle, and cannot be rolled
into wires or pounded into sheets. The non-metals exist in two of the three states of matter at room temperature:
gases (such as oxygen) and solids (such as carbon). The non-metals have no metallic luster, and do not reflect
light. They have oxidation numbers of ±4, -3, and -2.
The Lanthanide Series
They include:
Lanthanum
Cerium
Praseodymium
Neodymium
Promethium
Samarium
Europium
Gadolinium
Terbium
Dysprosium
Holmium
Erbium
Thulium
Ytterbium
Lutetium
Actinide Series
y include:
Actinium
Thorium
Protactinium
Uranium
Neptunium
Plutonium
Americium
Curium
Berkelium
Californium
Einsteinium
Fermium
Mendelevium
Nobelium
Lawrencium
Rare Earth Elements
thirty rare earth elements are composed of the lanthanide and actinide series. One element of the lanthanide series and
t of the elements in the actinide series are called trans-uranium, which means synthetic or man-made. All of the rare
h metals are found in group 3 of the periodic table, and the 6th and 7th periods.
Metals vs. Non-metals
Chemical Properties
Metals
•Usually have 1-3 electrons in their outer shell.
•Lose their valence electrons easily.
•Form oxides that are basic.
•Are good reducing agents.
•Have lower electro negativities.
Physical Properties
Metals
•Good electrical conductors and heat conductors.
•Malleable - can be beaten into thin sheets.
•Ductile - can be stretched into wire.
•Possess metallic luster.
•Opaque as thin sheet.
•Solid at room temperature (except Hg).
The Atom
•Atoms are made up of three different subatomic particles.
•The neutrons and protons exist in the central part of the atom called the nucleus. The electrons exist outside of
the nucleus in shells or energy levels.
•Since the neutrons and protons are far more massive than electrons nearly all of the mass of an atom is in the
nucleus.
•In a neutral atom the numbers of electrons and protons are the same. We say “the charges are balanced”.
The Subatomic Particles
•Protons are positively charged and Neutrons are neutral. Therefore the nucleus is positively charged.
•Electrons are negatively charged
•Protons and neutrons are bound together by a very strong force in the nucleus and therefore are not involved in
chemical reactions.
•Electrons exist in the outer parts of an atom and therefore are able to interact with the electrons of other atoms
resulting in chemical reactions.
Definitions
Atomic Number (Z) : the number which indicates how many protons (or electrons) are in a neutral atom. The
periodic table is organized by atomic number.
Mass Number (A): the number of protons and neutrons in an atom
Number of neutrons (N): The mass number minus the atomic number
(ie. N = A – Z )
The Bohr Model of the Atom
•the Bohr model of the atom suggests that :
–electrons can only travel in special orbits: at a certain discrete set of distances from the nucleus with specific
energies.
–The electrons do not continuously lose energy as they travel. They can only gain and lose energy by jumping
from one allowed orbit to another, absorbing or emitting electromagnetic radiation when they do.