Summary Grade 9 Science Study Note Chemistry 2019/2020
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Course
Science
Institution
9th Grade
This study note covers a simple chemistry review, with other topics such as ions, compounds, polyatomic ions, word equations, counting atoms, reactions, acids and bases. It is a simplified version of the Grade 9 Science course with clear and easy definitions/steps to follow!
Subatomic particles:
★ Made of protons, neutrons and electrons
★ Electrons are negative
★ Protons are positive
★ Neutrons are neutral (0)
★ Nucleus has protons and neutrons
★ Electrons orbit the nucleus
Structure of atoms:
★ Mass number is equal to protons plus neutrons
★ Number of protons are equal to number of electrons
★ Valence electrons are electrons on the outer shell
Periodic table:
★ Three types of elements
★ Metals
★ Non-metals
★ Metalloids
★ Vertical columns are groups
★ Horizontal rows are periods
Diagrams:
★ Bohr Rutherford
★ Lewis dot
Elements and compounds:
★ Elements can’t be broken down in chemical reactions
★ Compounds have two or more elements sharing or transferring electrons causing bonds
Ions and ionic charge:
Ion:
★ An atom that has gained or lost electron/s so it can fill its outer shell
★ Can have positive or negative charge
★ Number of protons and electrons are not equal
★ Lose electrons=positive=cation
★ Gain electrons=negative=anion
★ Number of valence electrons relates to placement on the periodic table (columns)
Ionic bonding:
, ★ Formed when one atom gains electrons and the other loses them
★ Opposites attract
★ That creates a bond between them
Ionic compounds:
Ionic compounds:
★ Formed when a metal and nonmetal combine to make a neutral compound
★ Electrons from metals to nonmetals
★ Opposite charges form attraction between ions
Naming:
★ Metal goes first
★ Nonmetal second
★ Add suffix -ide onto the end of nonmetal
Transition metals:
★ Some transition metals have more than one ionic charge
★ We use roman numerals to determine the charge
★ Silver is always +1
★ Zinc is always +2
★ The other transition metals that have multiple are copper, iron, lead and tin
Criss cross rule:
★ Can determine number of atoms in ionic compounds
★ Criss cross the charges NOT the valence electrons
★ ONLY between metal and nonmetal
★ Find lowest common denominator (if one has two and so does the other, they are both
ones) this creates a neutral compound
★ Ionic crystal compounds: just having one bond (two atoms wouldn’t be enough, it would
be microscopic, so we therefore need way more, and in a pattern so they all bond)
Polyatomic ions:
Polyatomic ions:
★ Group of atoms that usually stay together carrying an overall ionic charge
★ Example: ammonium and carbonate
Naming with polyatomic:
★ Follow same rules as ionic compounds
★ Steps:
○ Find ionic charge for each part of the compound
○ Write symbol below charge
○ Crisscross numbers and use as subscripts
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