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Introduction to Chemistry. What do you already know about chemistry?. Chemistry. The science that studies the interactions of elements of the periodic table and the properties of the elements. Periodic Table.
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Chemistry • The science that studies the interactions of elements of the periodic table and the properties of the elements.
Periodic Table • An arrangement of elements into rows and columns according to similarities in their properties. They can be metals, non-metals or metalloids.
Element • A substance composed of only one kind of atom. It cannot be broken down chemically into simpler units.
Atom • The smallest particle of an element that is still characteristic of that element.
Atomic Number • The number of protons in each element is equal to the atomic number. It is usually above the symbol in the periodic table. They start at 1 (hydrogen) and increase as you move across the periodic table.
Groups • The vertical columns on the periodic table. They count from 1-18. Elements in the same group have similar chemical behavior.
Periods • The horizontal rows on the periodic table. They count from 1-7. Elements in the same period have the same number of electron energy levels.
States of Matter • Elements can be solid, liquid, or gas. There is usually a key on the periodic table to guide you.
Metals • Substances that are shiny, solid at 25˚C (except mercury), and are good conductors of heat and electricity. They are malleable (can be pounded into shape), and ductile (pulled into wires). They are found on the left of the staircase on the periodic table.
Non-metals • These elements are not shiny or bendable. They are usually brittle and they do not conduct heat or electricity. They can be solids, liquids or gases. Non-metals are found to the right of the staircase.
Metalloids • These elements have some characteristics of metals and non-metals. They are generally very hard solids with very high melting points that are either non-conductors or semi-conductors of electricity. Metalloids are next to the staircase.
Compounds • Compounds are made up of more than one type of atom, one a metal and one a non-metal, combined in a fixed proportion. i.e., NaCl or HCl
Molecules • Molecules are made up of more than one atom, all of which are non-metals. Molecules can be the same atom, or different atoms. i.e., H2O or H2
Alloys • Two metals mixed together to make a new substance.