This document provides information about key chemistry concepts including: - Chemistry is the study of connections between the everyday world and molecular world, explaining properties and behaviors of matter. - Atoms are the smallest component of an element, having its chemical properties. Elements are pure substances made of one type of atom. - The nucleus contains protons and neutrons at the center of an atom. Protons have a positive charge, neutrons have no charge, and electrons orbit around the nucleus and have a negative charge. - The periodic table organizes elements by atomic number and similar properties, with periods representing electron shells and groups representing outer electrons.

1. CHEMISTRY
CHAPTER 7 PAGE 245
SCALE OF THE UNIVERSE – INTERACTIVE
YR 8 CHEM WIKI

3. Dan Radcliffe re-cites the Periodic table song
First 10 elements song
Atomic theory video (duration: 3 minutes)
‘I’m atoms’ song video (duration: 4 minutes)

4. • Chemistry - the study of connections between the everyday world and the
molecular world. Chemists use atoms and molecules to explain and predict
the structure, properties and behaviours of matter. For example, chemistry
provides the molecular explanations for food storage, cooking, flavour, smell,
steam, ice and cleaning products.

5. • Atom (physics and chemistry) the smallest component of an element
having the chemical properties of the element
• Element
a pure substance made of only one kind of atom - neutral
electrical - the number of protons and electrons is equal and balanced (eg of
elements are Hydrogen - H, Oxygen - O, Sodium - Na, Chlorine - Cl, Carbon - C,
Magnesium - Mg)

7. • Nucleus
the positively charged dense
centre of an atom - composed of protons and
neutrons
• Proton
A sub-atomic particle that has a
positive charge and that is found in the
nucleus of an atom
• Neutron
A sub-atomic particle that has no
charge and that is found in the nucleus of an
atom
• Electron
a very small negatively charged
particle that orbits around the nucleus at
great speed.

8. • Atomic Number
The number of protons in
the nucleus of an atom (the number of
protons and electrons is equal in an element)
• Atomic Mass Total mass of the protons and
neutrons in an atom, measured in atomic
mass units

9. Go to the Yr 8 Chem wiki and complete the Atomic Number and Mass activities

10. • Compound - a substance formed by chemical union of two or more elements
or ingredients in definite proportion by weight eg Water = H2O, Salt = NaCl,
Carbon Dioxide = CO2

11. • Crystal lattice a grid-like
structure of atoms or ions
where each particle is
bonded to all of its
neighbouring atoms

12. • Periodic Table
A table that shows the elements, their atomic number,
symbol, and average atomic mass; elements with similar chemical properties
are grouped together.
• Periodic Table Periods - Horizontal rows - elements that have same number
of orbital shells, arranged by atomic number (protons) The number of
electrons in the outer shell increases by one from left to right across the row.
• Periodic Table Groups - Vertical columns - elements that have similar
chemical and physical properties due to their outermost electrons.

14. Periods represent electron shells or orbital levels

15. Groups represent the elements that have the same number of electrons in their
outer orbital.

16. • Valence Electron an electron in the outer shell of an atom which can
combine with other atoms to form molecules
• Electron Orbital shell an energy level of electrons at a characteristic average
distance from the nucleus of an atom
• Electron configuration the arrangement of electrons in the orbitals of an
atom eg 2, 8, 8
• Ion when an atom loses electrons (become more positive) or gains electrons
(become more negative) it has become an ION. The study of chemistry is
based on the ability of atoms to either lose, gain or share electrons

17. • Metals (elements) any of a class of elementary substances, as sodium,
magnesium, or copper, all of which are crystalline when solid and many of
which are characterized by opacity (can't see through it), ductility (easily
reshaped eg lead), conductivity (electrical current), and a unique lustre (shine)
when freshly fractured or cut. Can easily lose electrons and become positively
charged - positive ions - (Na - Na+, Mg - Mg++)
• Non-metals (elements) chemical elements that are generally poor conductors
of heat and electricity, and they form negative ions - (Oxygen - O double
negative, Chlorine - Cl negative)