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What do we know about the periodic table? Please explain. All matter is made of tiny particles called atoms Atoms are made of even smaller particles: protons, neutrons, electrons Protons-A particle with a positive charge in the nucleus of an atom Neutron-A particle with no charge in the nucleus of an atom Electron-A particle with a negative charge in an atom Charge-Certain amount of electricity Protons and neutrons are packed together in very tiny nucleus The nucleus is the center of an atom; consists of neutrons and protons A chemical bond forms when two or more atoms share a transfer of electrons When a neutral atom is not bonded with other atoms, it has the same number of protons and electrons For example, a lithium atom has 3 electrons, 3 protons, and 4 neutrons. The atom is neutral because the positive and negative electrons cancel each other out Elements are substances made up of only one kind of atom They are the simplest forms of matter. Examples are oxygen and calcium The atomic # is the number of protons in an atom. Every element has a unique atomic # An atom is the smallest particle of an element that has the properties of that element There are at least 111 officially named elements and about 90 exist naturally on earth Each element has a chemical symbol which is a one or two letter symbol that represents the element. The first letter is always capitalized. The periodic table is a table that shows the names and symbols of elements and is organized by atomic # and electron arrangement The periodic table has two main sections: metals and nonmetals Metal is an element found on the left side of the periodic table; often a shiny solid that can conduct heat and electricity Nonmetal is an element found on the right side of the periodic table; often a gas or dull solid that does not conduct heat or electricity A semi-metal is an element that has properties of both a metal and nonmetal; located between metals and nonmetals on the periodic table. The natural form of an element-as single atoms or as groups of bonded atoms-is a physical property. Elemental form is used to classify elements into three categories monatomic, diatomic, and polytomic Monatomic-existing as single atoms Diatonic-Existing as pairs of bonded atoms Polyatomic-Existing as groups of three or more bonded atoms Subscript is a number written just below the writing line; in chemical formulas, it tells the number of atoms of a certain element