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This comprehensive overview explores the structure of matter, focusing on atoms and elements. It defines matter as anything with mass and volume, emphasizing the law of conservation of matter that states it cannot be created or destroyed. Key concepts include the atomic structure, the role of protons, neutrons, and electrons, and the characteristics of elements classified into metals, nonmetals, and metalloids. The differences between compounds and mixtures are outlined, along with insights into chemical bonds and reactions, providing a foundational understanding of chemistry and materials science.
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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).
