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Atoms, Molecules, Compounds • All matter is made of one or more elements. Elements are pure substances that cannot be broken down by any chemical or physical means. Elements A substance consisting of a single type of atom. It cannot be broken down into different kinds of matter. http://www.rentrain.com/reso urces/Helium%20Safety.jpg http://www.reachoutmichigan.org/fune xperiments/agesubject/lessons/handout s/helium.GIF Atoms The basic component of all matter. The atom is the smallest particle of an element that has all of the chemical properties of that element. Atoms consist of a nucleus of protons and neutrons surrounded by electrons. http://www.ktf-split.hr/glossary/image/atom.gif • Atoms are composed of 3 subatomic particles called protons, neutrons and electrons. • The center of the atom is called the nucleus. It contains protons and neutrons. • Circling around the nucleus is 1 or more electrons. • Atoms are different from each other because each element’s atoms have different #s of the subatomic particles. • The electron is found moving around the outside of the nucleus. • The electron has a (-) electric charge. • The has a mass of 0.0005 amu. (The mass of the electron is so small compared to the proton and neutron that it is ignored.) e • Protons are located in the center core of the atom called the nucleus. • Protons have a positive electric charge (+1) • Protons (p+) have a mass of 1 amu (atomic mass units). Structure / Parts of the Helium Atom Electron Neutron Proton • Neutrons are also located in the nucleus. • Neutrons are electrically neutral. They do not have a charge. • Neutrons (n0) have a mass of 1 amu. AMU = protons + neutrons + electrons The periodic table gives the following information about each element and its atoms. • Atomic Number • Atomic Mass • Element Symbol Sample Periodic Table • The symbol is an abbreviation for the name of each element. It’s either 1 or 2 letters with the 1st letter capitalized. • The atomic number is the smaller of the 2 numbers. This number tells us the number of protons and the number of electrons in the atom. • The atomic mass # is the sum of the protons, neutrons, and electrons. • This number is used to find the number of neutrons. • Neutrons = Atomic mass (rounded) – atomic number A.M. – A.N. = n0 Combinations of Elements: Compounds A substance formed from two or more elements, with a fixed ratio determining the composition. The elements lose their individual chemical properties and the compound has new properties. http://www.awwu.biz Molecules Compound of two or more atoms, the smallest unit of chemical compounds. The smallest particle of a substance that has all of the physical and chemical properties of that substance. http://www.awwu.biz Combinations of Elements: Mixtures A substance consisting of two or more substances mixed together. Mixtures can usually be separated by mechanical means. Two or more substances mixed together in such a way that each remains unchanged. http://www.seelecttea.com/ Formulas The formula which identifies the atoms and the number of each type of atom in the molecules of a compound. The number and types of atoms in a molecule. Glucose C6H12O6 Formulas 6C6H12O6 Carbon Hydrogen Oxygen Elements in the compound Formulas: Subscripts 6C6H12O6 Number of atoms of each element in a molecule of the compound: Carbon = 6 Hydrogen = 12 Oxygen = 6 Formulas: Coefficients 6C6H12O6 Number of molecules = 6 molecules of glucose