Presentation on theme: "Grade 9 - Chemistry Section topics You should study this material!"— Presentation transcript:
Grade 9 - Chemistry Section topics You should study this material!
What is matter? Categorized matter. Physical properties of matter. Things that you can touch or see or smell. Flash cards of 12 properties We focused upon Density Calculate using the equation: Calculate density from slope of a Volume vs. Mass graph. GRASP! Identify physical properties from examples. Physical change - what is it?
Chemical properties of matter. Specifically, how atoms react with other atoms - Reactivity! Toxicity, etc. Chemical change – what is it? (Something about new matter being created…) Combustion, corrosion, etc. Identifying chemical change versus physical change and why.
History of the atom – early models up until the model as understood in the 1920’s. Aristotle, Alchemists Dalton, Thomson, Rutherford, Bohr Bohr-Rutherford diagrams for the first 20 elements. You should know and recognize the symbols for the first 20 elements PLUS these transition metals: Iron, Nickel, Copper, Zinc, Silver, Gold, Mercury, Tin, Lead. Recognize the Atomic Number & Mass.
We missed the history of the periodic table but it was covered briefly in the movie we watched. Suffice to say, it evolved from early models. Russian scientist Mendeleev presented his version, now widely accepted, in 1869. Mendeleev’s table is organised into periods and groups. Periods run horizontally and basically count protons. Groups run vertically.
Groups on a periodic table place elements together that have similar physical & chemical properties. You should know these groups: Alkali metals Alkaline earth metals Halogens Noble gasses Metalloids You should also know the broad grouping of metals versus non-metals. Divided by the metalloids…
Groups of elements have the same number of Valence Electrons. This is the primary characteristic of each group on the periodic table! Lewis dot diagrams for the first 20 elements. An isotope is an atom with a different number of neutrons. (That’s all you need to know) Atoms want to be stable. This is done when the valence layer is full. To do this, add or remove electrons to the outer layer (to form an octet).
Ion – when an atom has more or fewer electrons than the number of protons. Elements in groups 1 – 3 tend to lose electrons. When they do, they lose negatively charged electrons and as a result, have a net positive charge. Elements in groups 5 – 7 tend to gain electrons. They will then have a net negative charge. Group 4 atoms may gain or lose electrons – that’s for later study.
Noble gasses don’t ionize at all! Positively charged ions will be attracted to negatively charged ions. An ionic molecule is formed when a positively charged ion joins with negatively charged ions. Example sodium ions are attracted to chlorine ions to form sodium chloride. You then did a worksheet on molecules and naming.
And thus, our studies in Chemistry are done for Grade 9… In Grade 10, you will continue your study of chemistry where we have left off this year. So don’t lose your notes!