SNC1D: CHEMISTRY Atoms, Elements and Compounds Exam Review

Mixture a substance made of different pure substances

Heterogenous not uniform

Homogenous uniform (in composition and properties) Ex. a solution

Pure Substance a substance made of only one kind of particle

Element a pure substance made of only one kind of atom

Compound a pure substance made of more than one type of atom that have been chemically bonded together

Particle Theory of Matter 1.All matter is made of tiny particles. 2.Different pure substances are made up of different types of particles. 3.Particles are always in constant random motion. 4.The particles in a substance attract each other. 5.The particles of a substance move faster when heated.

Physical change a change in which no new substances are produced Ex: ice melting

Chemical Change a change in which new substances are produced Ex: iron rusting

Physical Property description of the nature of a substance Ex: gold is a relatively soft metal

Chemical Property description of how a substance reacts with other substances Ex: iron rusts

Element Symbols Cacalcium Clchlorine Mgmagnesium Nasodium

Element Names OxygenO IronFe ArgonAr TungstenW

Chemical families IAalkali metals IIAalkaline earth metals VIIAhalogens VIIIAnoble gases

Metals Shiny Malleable Good conductors Found on the left side of the Periodic Table (most reactive: Alkali Metals)

Non-Metals Dull Brittle Poor conductors Found on the right side of the Periodic Table (most reactive: Halogen; least: Noble Gases)

Atomic Number the number of protons in the nucleus

Atomic Mass the number of protons + neutrons in the nucleus

Isotope an atom with a different number of neutrons and therefore a different mass

Experiments Thomson’s cathode ray experiments: atoms contain electrons Rutherford’s gold foil scattering experiments: atoms contain small, dense, positively-charged nuclei Bohr’s flame tests: electrons are only found in certain orbits (energy levels)

Atomic Numbers

Bohr Diagram Magnesium:

Rows and Columns Elements in the 3 rd period (row) all have 3 orbits around the nucleus. Elements in the 1 st column all have 1 electron in their outer (valence) orbit.

Word Equations sulphur + oxygen→sulphur dioxide reactants product

Word Equations sodium hydroxide reacts with hydrochloric acid to produce sodium chloride and water

Word Equations Silver chloride and calcium nitrate are produced when calcium chloride reacts with silver nitrate.

Valence Shell An atom wants 8 electrons in its outer (valence) shell to be stable.

Valence Shell How many electrons do elements in the following families gain or lose to become stable? i) IA lose 1 ii) IIA lose 2 iii) VIIA gain 1 iv) VIIIAneither lose nor gain

Ionic Compound In an ionic compound, a positive metal ion is electrically attracted to a negative non-metal ion.

Molecular Compound In a molecular compound, non-metals share electrons.

Covalent Bonding This sharing is a covalent bond.

Ionic Compound NaCl must be an ionic compound because it contains a metal.

Methane