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Matter and the Periodic Table
Vocabulary
1. Chemistry: the study of matter
2. Matter: anything that has mass and takes up space
3. Element: substance that cannot be broken down into other substances; all atoms of the
same element have the same number of protons
4. Atom: the smallest amount of an element that still has the properties of the element; it is
made of protons, neutrons, and electrons
5. Proton: a positively charged, heavy particle in the nucleus of an atom; the number of
protons in an atom determines which element the atom is
6. Neutron: a heavy particle with no charge in the nucleus of an atom
7. Electron: a very light, negatively charged particle that occupies the space outside the
nucleus of an atom
8. Nucleus: the central part of an atom that contains the protons and neutrons; almost all
of the mass of the atom is in the nucleus
9. Group: a column (going up and down) of elements on the Periodic Table (also called a
family)
10. Period: a row of elements (going across) on the Periodic Table
Atomic Structure Notes
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Atoms are made of 3 particles: protons (+), neutrons (o), and electrons (-)
Protons and neutrons together make up the nucleus of an atom
Electrons move very quickly around the nucleus in an electron cloud
The charges on protons (+) and electrons (-) cause them to be attracted to each other.
This attraction is what holds an atom together (similar to a magnet).
Atoms are mostly empty space
The protons and neutrons are heavy particles and make up almost all of the mass of the
atom; therefore almost all of the mass of the atom is in the nucleus
The electrons are very, very light and contribute almost no mass to the atom
The number of protons in an atom is called the atomic number. It identifies the atom as
a particular element. For example, all oxygen atoms have 8 protons and any atom that
has 8 protons is oxygen.
The number of electrons in an atom will always be equal to the number of protons (the
negative charges balance out the positive charges).
The number of protons + the number of neutrons is called the atomic mass.
Periodic Table Notes
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An element's properties can be predicted from its location in the Periodic Table.
The Periodic Table of Elements was first arranged by Dmitri Mendeleev in 1869.
The Periodic Table is arranged in order of increasing atomic number (number of protons).
A column (up and down) on the Periodic Table is called a group or family. There are 18
groups.
 The elements in a group have similar characteristics (look similar, have similar properties)
 A row (going across) on the Periodic Table is called a period. There are 7 periods.
 The elements to the left of the zig-zag line on the Periodic Table are the metals. They
have properties of being shiny, malleable, ductile, and good conductors of heat and
electricity.
 The elements to the right of the zig-zag line on the Periodic Table are the non-metals.
They have properties of being dull, brittle, and poor conductors of heat and electricity.
 The elements between the metals and non-metals next to the zig-zag line are called
metalloids. They have some properties of metals and some properties of non-metals.
 Group 1 on the Periodic Table is called the Alkali Metals. They are very reactive metals
(and the most reactive of all the elements on the table).
 Although hydrogen is at the top of Group 1, HYDROGEN IS NOT AN ALKALI METAL. It
is a very reactive gas (not a metal).
 Group 2 is called the Alkaline Earth Metals. They are also reactive metals.
 Group 17 is called the Halogens or Halides. They are very reactive non-metals.
 Group 18 is called the Noble Gases. These gases are completely unreactive (they do not
make compounds with any other elements).
 The large block of elements in the middle of the Periodic Table is called the Transition
Metals. These metals are very good conductors and are not very reactive, which makes
them good for wiring (copper, zinc, gold)
At the end of the unit, you should be able to use the Periodic Table to get the following
information about any element:
 The number of protons
 The number of neutrons
 The number of electrons
 Whether the element is a metal, non-metal, metalloid, or Noble gas
 Some properties of the element (metals - shiny, malleable, ductile, good
conductors of heat and electricity; non-metals - dull, brittle, poor conductors of
heat and electricity; Noble gas - completely unreactive gas)
 How reactive the element is: Group 1 - most reactive elements of all
Group 2 - very reactive metals
Group 17 - very reactive
Group 18 - completely unreactive
 Whether the element is a solid, liquid, or gas at room temperature