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Ch. 3 Atoms, Elements & the Periodic Table. Structure of Matter Is anything that has mass and takes up space. What does not have matter? Light, heat, emotions Law of conservation of matter – states that matter is not created or destroyed; it only change its form. Define an atom ?
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Ch. 3 Atoms, Elements & the Periodic Table • Structure of Matter • Is anything that has mass and takes up space. • What does not have matter? Light, heat, emotions • Law of conservation of matter – states that matter is not created or destroyed; it only change its form. • Define an atom? • “Building blocks” of matter; smallest particles of an element that still have all the properties of that element
Element – a substance that can’t be broken down into simpler substances. • Ex. Au, Cu, O, C, N, H, Na, Cl, F, Ca, Mg, Sn, Pb, etc. • Atom – the smallest part of an element. • 1. protons = + charge, in nucleus • 2. neutrons = no charge, in nucleus • 3. electrons = - charge, in electron clouds.
Sizes of Atoms – 1 million lined in a row make up the thickness of a human hair. • Atomic # = # of protons in the nucleus. It is the top number on a period table • Mass # = total number of protons and neutrons in the nucleus. • Mass # - Atomic # = # of neutrons. • Atomic Mass – is the average weighted mass of the isotope of an element. It is the number on the bottom of the period table
Energy “Shells” Levels = the area outside the nucleus where electrons are found; shells fill from inside out • 1st = 2, 2nd = 8, 3rd = 18, 4th = 32, etc. • Isotopes = atoms of the same element with different mass numbers. The neutrons differ from one atom to the next. • Classification of Elements • Metals – All metals except mercury are solid at room temp., generally shiny & a good conductor of electricity, most are malleable, ductile. Locate these on a periodic table • Nonmetals – Most are gas at room temp., usually dull in looks, poor conductor of electricity, and usually involved in chemicals of life. Locate these on the table • Metalloids – chara. of both metals and nonmetals; locate these on the table.
Compound – a substance that is composed of atoms of 2 or more different elements that are chemically combined. • Chemical Bond – forces that hold the elements together in a compound. • 1. Ionic Bond – a forced attraction between oppositely charged elements. • Electrons are gained or lost due to this bond. • Ex. NaCl, LiF, HCl, etc. • The net electrostatic charge is zero when elements form an ionic bond. • 2. Covalent Bonds – This bond is created when atoms share electrons between them. • The atoms that form a covalent bond usually have the same charge. • Ex. H2O, CH4, H2, N2, Cl2, etc.
Mixtures – a combination of 2 or more substances. • 1. Heterogeneous Mixture =One can distinguish the substances that make up the mixture. • Ex. Toss Salad, Pizza, Mixed vegetables, etc. • 2. Homogenous Mixture = One can’t distinguish the substances that make up the mixture. • Ex. Pop, Kool-aid, Tomato soup, etc. • Solutions – example of a mixture; a mixture where one substance dissolves in another substance. • Example slat water or sugar water • Chemical Reactions – change of one or more substance into other substance(s).
