Download Grade 10 Applied Science – Unit Chemistry

Grade 10 Applied Science – Unit Chemistry
Atoms and Molecules
TRC DVD 9754
Everything in our world is made of atoms…and groups of atoms called molecules. Atoms consist of
subatomic particles: protons, neutrons and electrons. (Now, we know that there are even smaller
subatomic particles such as quarks….hmmm….makes you wonder).
An atom has a nucleus that holds protons and neutrons. Electrons orbit the nucleus.
Protons have a positive charge and electrons have a negative charge, and just like a magnet, these
opposite charges attract. That is, protons attract electrons. The negative electrons are attracted to the
atom’s nucleus because the nucleus contains positive protons. The attractive force is called
ELECTROMAGNETIC FORCE.
Wait…protons are positively-charged AND like charges repel. How do the protons stay together in the
nucleus if their charge repels one another? This force is NUCLEAR FORCE. It is the strongest force
known. A nuclear explosion occurs when this force is pulled apart.
If everything is made of atoms, why do all things not look alike? At this point, we study the PROPERTIES
of the elements. Atoms with identical properties and the same number of protons in their nuclei are
elements. For example, every atom of oxygen has eight protons and possesses identical properties (e.g.,
natural state at room temperature is a gas, colourless).
The number of protons in the nucleus is the ATOMIC NUMBER. If the element oxygen has eight protons,
its atomic number is eight.
The ATOMIC MASS is the number of protons PLUS the number of neutrons.
The millions of substances on Earth come from the chemical combination of two or more different
elements in a fixed ration. This is CHEMICAL BONDING to form a COMPOUND. For example, water is
a compound of two parts of hydrogen plus one part of water (…H2O).
A chemical bond is due to the electrons of the molecule.
 If one element gives an electron while a different element takes the electron, a chemical bond
called an IONIC BOND is formed. The element giving the electron(s) creates a positivelycharged ION…called an ANION. The element taking the electron(s) becomes a negativelycharged ion called a CATION.
 If a bond occurs because two elements share electrons, the bond is a COVALENT BOND.
Task

Watch the DVD Atoms and Molecules and answer the following questions
1. According to the DVD, what is the smallest particle of matter?
2. Describe a typical model of an atom including the subatomic particles.
3. How does electromagnetic force hold subatomic particles together?
4. What is nuclear force?
5. What makes one atom different from another atom?
6. Approximately how many elements occur in nature?
7. What does an element’s Atomic Number tell you?
8. How do elements join together to make different substances?
9. What is the relationship between compounds and molecules?
10. What is a covalent bond? Provide an example…
11. What is an ionic bond? Provide an example of a compound formed by an ionic bond…
12. What are the Phases of Matter? How does VIBRATION of atoms relate to the properties of
matter?