Chapter 5 Review

• Valence electrons are the electrons in the outermost shell of an atom.
• Isotopes are different forms of an element with the same number of protons but different numbers of neutrons.
• Periodic table is a table that shows the elements, their atomic number, symbol, and average atomic mass; elements with similar chemical properties are grouped together.
• The organization Periodic Table is organized the elements in rows (called periods) and columns (called groups) according to increasing atomic number.
• Alkali Metals are elements in group 1. They are soft and have low density and melting points. They are also very reactive.
• Alkaline-Earth Metals are elements in Group 2. They are highly reactive (less than Alkali Metals), and they burn in air when heated
• Bohr's Atomic Model describes that atoms have levels surrounding the nucleus where electrons are found. Levels can hold different amounts of electrons depending on their distance from the nucleus.
• Rutherford's Atomic Model describes an atom is mostly empty space with a small, dense positively charged nucleus in the centre. He identified the proton and the neutron in the nucleus, and electrons revolve all around it
• Dalton's Atomic Theory described elements in terms of atoms, believed to be small, indivisible particles that all make up matter. All atoms of the same element are identical in mass and size, but different elements are made up of different atoms.
• Thomsom's Atomic Model describes the atom as a tiny positively charged sphere with electrons orbiting it.
• The Standard Atomic Notation is the abbreviation for the atomic number of an element. It shows the chemical symbol, the mass number and the atomic number of the isotope
• The period on the Periodic Table represent the number of shells that an element can occupy.
• The groups on a Periodic Table represent the number of electrons in the outer shell.
• Metals are on the left side of the Periodic Table. They are solid at room temperature. They also are described to be shiny. They are good conductors of heat and electricity , and they are malleable and ductile.
• Non-metals are on the right side of the Periodic Table. Some are gaseous and some are solids. They are described to not be shiny. They have poor malleability and ductility, and they are poor conductors of heat and electricity.
• Halogens are non-metals that are found in group 17 of the periodic table. They are highly reactive and corrosive, and their melting points increase as you move down the group.
• Noble Gases are non-metals in group 18 of the periodic table. They are described to be odourless and colourless gases. They are stable and are non-reactive.
• The size of the atom increase as you move down periods on the table, therefore the valence electrons are further away from the nucleus.
• Atoms are composed of three subatomic particles: protons, neutrons, and electrons.
• Protons are positively charged and is found inside the nucleus. They have a mass of 1.
• Neutrons are neutrally charged and is found inside the nucleus. They have a mass of 1.
• Electrons are negatively charged and orbit the nucleus. They have a mass of 0.