Grade 9 Chemistry: Periodic Table Elements

Chemical Properties and Reactions

• A substance's ability to combine chemically with other substances is described by its reactivity.
• Rutherford's experiment demonstrated that alpha particles have a positive charge.

Chemical Formulae

• In the chemical formula Na₂HPO₄, the subscript '2' represents the number of sodium atoms present.
• The coefficient in the chemical formula 3H₂O represents the number of molecules of water present.

Atomic Structure

• Rutherford's experiment involved using gold foil to demonstrate that atoms are mostly empty space.
• Rutherford concluded that atoms are mostly empty space because most alpha particles passed through the gold foil without being deflected.
• Rutherford deduced that the nucleus of an atom is positively charged because the alpha particles were deflected by the positive charge.

Compounds and Mixtures

• A compound is a substance formed by the chemical combination of two or more different elements.
• The key difference between a compound and a mixture is that the components of a compound are chemically bonded, whereas the components of a mixture are not.
• A uniform mixture, also known as a solution, is a type of mixture in which the components are evenly distributed.

Periodic Table

• Elements in the same group have the same number of valence electrons.
• Elements in the first period of the periodic table have a specific number of valence electrons.

Properties of Elements

• Non-metals are typically brittle and break easily.
• Metalloids share some properties with metals, but not all.
• The most reactive non-metal in its group is fluorine.

Atomic Models

• Niels Bohr's model of the atom suggests that electrons move around the nucleus like planets around the sun.
• The modern Quantum Model of the atom features an electron cloud, which is a region where electrons are likely to be found.

Atomic Theory

• According to Dalton's Atomic Theory, elements are composed of small, indivisible particles called atoms.
• The atomic number of bromine is 35.
• The symbol for the element tungsten is W.
• The nucleus of an atom contains protons and neutrons.

Prepare for your Grade 9 Chemistry class at Windsor Park Collegiate by mastering the periodic table elements and their symbols. Test your knowledge on elements such as Hydrogen, Oxygen, Sodium, and more!