CHEMISTRYCHAPTER 7 PAGE 245

SCALE OF THE UNIVERSE – INTERACTIVE

YR 8 CHEM WIKI

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

• 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.

• 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)

• 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.

• 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

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

• 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

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

• 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.

Periods represent electron shells or orbital levels

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

• 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 configurationthe 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

• 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)