Grade 10 Academic Science – Chemistry
Periodic Table – Properties of Elements
TRC DVD8163
The science of chemistry is the study of the properties of matter. Is it solid, liquid or gas? Is it
hard or soft? Shiny or dull? These are PHYSICAL PROPERTIES – characteristics that can be
observed. CHEMICAL PROPERTIES describe the way an element behaves in a chemical
reaction.
The Periodic Table arranges the elements to reveal patterns in their properties. From its position
in the table, you can guess an element’s reactivity, size and other properties.
The NUMBER and ARRANGEMENT of the electrons in an atom is crucial to how the element will
behave AND how electrons will bond to other atoms to make molecules. The outer shell of
electrons (called VALENCE SHELL) is the most important in determining properties since it is
these electrons that are usually involved in any chemical reaction.
Definitions
 ANION – A negatively-charged ion
 ATOMIC RADIUS – The distance from the centre of the nucleus of an element to the
outer edge of the electron cloud.
 BONDS – Forces that hold atoms together.
 CATION – A positively-charged ion.
 ELECTRON SHELL – A term for energy level
 GROUPS – The 18 VERTICAL COLUMNS in the Periodic Table. Each element in a
group has the same number of electrons in its outer shell
 FAMILY – Groups in elements in the Periodic Table based on similar CHEMICAL
PROPERTIES (e.g., alkali metals)
 ION – An atom or covalently-bonded molecule with an overall charge
 MOLECULE – The smallest particle of a substance which still displays the properties of
the substance. An elemental molecule contains one element, while an compound
molecule contains different elements
 PERIOD – Seven HORIZONTAL ROWS in the Periodic Table. Every element in a period
has the same number of electron shells.
 VLAENCE ELECTRONS – Negatively-charges particles in the outer electron shell of an
atom. These electrons are lost, shared or gain during bonding.
Questions
View the DVD and answer the following questions
1. What is the difference between a CHEMICAL PROPERTY and a PHYSICAL
PROPERTY?
2. Why do elements in the same family generally have similar chemical properties?
3. Why is the ARRANGEMENT of electrons in an element the key to understanding why
each element behaves the way it does?
4. How many PROTONS, ELECTRONS and NEUTRONS does Lithium have?
5. What factors impact the size of an atom’s valence shell?
6. Why are the ALKALI METALS so reactive?
7. What elements belong in the HALOGEN FAMILY? What properties make them similar?
8. Why is FLUORINE more reactive than IODINE?
Grade 10 Academic Science – Chemistry
Periodic Table
TRC DVD8159
The Periodic Table is a simple arrangement of chemical elements that REVEALS patterns. For
example, elements in the SAME COLUMN have similar physical and chemical properties.
In 1909, Ernest Rutherford discovered that all the POSITIVE ENERGY and nearly ALL THE
MASS of an atom were located at its centre – the NUCLEUS. The negative charged
ELECTRONS circled around the nucleus. This idea is the basis for the Bohr-Rutherford
Diagrams of elements and the layout of the Periodic Table.
Definitions
 ATOM – The small particles that make up MATTER consisting of a nucleus containing
protons and neutrons and surrounded by electrons
 ATOMIC MASS – The mass of an atom. It is the number of protons plus the number of
neutrons
 ATOMIC NUMBER – The number of protons in the nucleus of an atom. The number also
represents the number of electrons of an atom.
 CHEMICAL SYMBOL – An element’s one or two-letter code representing the element’s
name.
 ELECTRONS – Negatively-charged subatomic particles that orbit the nucleus of every
atom
 NEUTRONS – Subatomic particles with no charge located in the nucleus of an atom
 PROTONS – Subatomic particles with a positive charge located in the nucleus of an
atom
Questions
View the DVD and answer the following questions
1. Why is the atomic mass of hydrogen listed as 1.0079 atomic mass units on the Periodic
Table?
2. What is the difference between deuterium and tritium?
3. What does the ATOMIC NUMBER tell us about an atom?
4. What is an isotope?
Grade 9 Academic Science – Unit 3 Chemistry
Periodic Table: Structures of Atoms
DVD TRC8790 Section 6.1
The ATOMIC NUMBER is simply the number of protons in the nucleus. There is always one negatively
charged electron surrounding / outside / orbiting the nucleus for each positively charged proton in the
nucleus.

Hydrogen has one proton and one electron. The Atomic Number of hydrogen is one.

Helium has two protons and two electrons. The Atomic Number of helium is two.

NOTE: Each element in the Periodic Table reading left to right in each row (…each row is
called a Period) has one more proton…and as such, the Atomic Number increases by one.
The ATOMIC MASS number is the number of protons plus the number of neutrons in the nucleus.

Hydrogen has one proton and zero neutrons. The Atomic Mass of hydrogen is one.

Helium has two protons and two neutrons. The Atomic Mass of helium is four.

NOTE: The Periodic Table often provides the Atomic Number and the Atomic Mass. I know
Atomic Number = number of protons. Thus, the Atomic Mass – Atomic Number = number of
neutrons.
Electrons move around the outside of the nucleus. The electrons occupy a series of shells (…or orbits…).
The shells are at different distances from the nucleus. Due to the attractive charge of the protons in the
nucleus, each shell holds a certain number of electrons.

Electron Shell #1 holds two electrons

Electron Shell #2 holds eight electrons

Electron Shell #3 holds 18 electrons….This seems somewhat confusing because it looks like
Electron Shell #3 holds only eight electrons. This hold true for only the first 20 elements.
Element 21 has four electrons shells with electron configuration of 2-8-9-2. Why? The
attractive charge of the nucleus, one electron from Electron Shell #4 is pulled into Electron
Shell #3. This occurs until Electron Shell #3 holds 18 electrons.
Elements in the same column are called a GROUP. Elements in the same group have the same number of
electrons in their OUTER ORBIT. This similarity gives the elements in the same group similar chemical
properties including reactivity, boiling and freezing temperatures, and electrical conductivity.

NOTE: Group 18 (…far right column of the Periodic Table) are called the NOBLE GASES.
This group has no free electrons in their outer orbits (i.e., the outer orbit is full). These
elements share a common chemical property: they do NOT readily react with other elements.
QUESTIONS
1. What happens to the number of electrons in the outer shell of an element has you read the Periodic
Table from left to right?
2. Why did Rutherford carry out his gold foil experiment in a vacuum?
3. What is the atom’s ATOMIC MASS?
4. What is the maximum number of electrons that can fit into the first, second and third electron shells?
5. Why would a chemist be interested in the number of electrons in the outer orbit of an element?
6. Why are NOBLE GASES so relatively non-reactive?
7. Describe how the elements are arranged in the Periodic Table so that their chemical properties can be
determined and described by the location of the element in the table.