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Elements and Compounds

Physical Science - Middle School

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Elements & Comp ounds © Copyright NewPath Learning. All Rights Reserved. 94-4826 Visit www.newpathlearning.com for Online Learning Resources. Elements Elements are the most basic forms of matter. Aluminum, sulfur, iron and oxygen are all examples of elements. These are pure substances that cannot be broken down into simpler substances. Scientists have identified over 100 elements that are present in our universe. Each element is made up of one type of atom which determines its properties. The Periodic Table groups elements by their atomic number. Each element is represented by a chemical symbol. H 1 Hydrogen He 2 Helium Ne 10 Neon Ar 18 Argon Kr 36 Krypton Xe 54 Xenon Rn 86 Radon Br Hg 35 Bromine Cl 17 Chlorine F 9 Fluorine O 8 Oxygen N 7 Nitrogen C 6 Carbon B 5 Boron Li 3 Lithium Na 11 Sodium K 19 Potassium Ca 20 Calcium Rb 37 Rubidium Cs 55 Cesium Fr 87 Francium Ra 88 Radium Ac 89 Actinium Rf 104 Rutherfordium Db 105 Dubnium Ce 58 Cerium Th 90 Thorium Pa 91 Protactinium Pr 59 Praseodymium Nd 60 Neodymium U 92 Uranium Np 93 Neptunium Pm 61 Promethium Sm 62 Samarium Pu 94 Plutonium Am 95 Americium Eu 63 Europium Gd 64 Gadolinium Cm 96 Curium Bk 97 Berkelium Tb 65 Terbium Dy 66 Dysprosium Cf 98 Californium Es 99 Einsteinium Ho 67 Holmium Er 68 Erbium Fm 100 Fermium Md 101 Mendelevium Tm 69 Thulium Yb 70 Ytterbium Lu 71 Lutetium No 102 Nobelium Lr 103 Lawrencium Sg 106 Seaborgium Bh 107 Bohrium Hs 108 Hassium Mt 109 Meitnerium 110 Ununnilium 111 Unununium 112 Ununbium Uub 114 Ununquaternium Uuq Uuu Uun Ba 56 Barium La 57 Lanthanum Hf 72 Hafnium Ta 73 Tantalum W 74 Tungstun Re 75 Rhenium Os 76 Osmium Ir 77 Iridium Pt 78 Platinum Au 79 Gold 80 Mercury Tl 81 Thallium Pb 82 Lead Bi 83 84 Bismuth Po Polonium Sr 38 Strontium Y 39 Yttrium Zr 40 Zirconium Nb 41 Niobium Mo 42 Molybdenum Tc 43 Technetium Ru 44 Ruthenium Rh 45 Rhodium Pd 46 Palladium Ag 47 Silver Cd 48 Cadmium In 49 Indium Sn 50 Tin Sc 21 Scandium Ti 22 Titanium V 23 Vanadium Cr 24 Chromium Mn 25 Manganese Fe 26 Iron Co 27 Cobalt Ni 28 Nickel Cu 29 Copper Zn 30 Zinc Ga 31 Gallium Al 13 Aluminum Mg 12 Magnesium Be 4 Berylium Si 14 Silicon P 15 Phosphorus S 16 Sulfur Se 34 Selenium As 33 Arsenic Ge 32 Germanium Sb 51 Antimony Te 52 Tellurium I 53 Iodine At 85 Astatine solid state at room temperature liquid gas not found in nature Periodic Table of the Elements Compounds A compound is a substance made up of two or more different elements that are chemically combined in an exact ratio. The chemical formula of a compound tells you which elements make up the compound and how many atoms of each element are found in a single molecule of the compound. Water is a compound that has a ratio of two hydrogen atoms to every one oxygen atom. If this ratio is changed to two hydrogen atoms to every two oxygen atoms, a different compound is formed. This compound, hydrogen peroxide, has different properties than water. It is used as cleaning agent, and you would not want to drink it! 2:1 ratio 2:2 ratio H2O O H H O H O H H2O2 O2 Atoms Atoms are the building blocks of elements. They are the smallest component of an element that still has the properties of that element. Every element is made up of atoms that have a unique structure. For example, an oxygen atom contains eight protons and eight neutrons in its nucleus. Eight electrons circle the nucleus in an electron cloud. Molecules A molecule is the chemical combination of at least two atoms. Many elements occur in nature as molecules, not as single atoms. Oxygen typically occurs as a molecule made up of two chemically bonded atoms, and is written in a chemical formula as O 2. Oxygen atom electron proton neutron nucleus Periodic Table of the Elements

Pause and Review Complete the graphic organizer. Illustrate or list information about each item. Describe how they are related to each other. Elements & Comp ounds _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ © Copyright NewPath Learning. All Rights Reserved. 94-4826 Visit www.newpathlearning.com for Online Learning Resources. Atom Element Molecule Compound

Elements and Compounds

Physical Science - Middle School

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