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element chemical symbol atomic nucleus protons atomic number neutrons electrons isotopes mass number atomic mass period group or family periodic trend Define these common chemistry vocabulary terms Element Any material that is made up of only one type of atom Use chemical symbol to abbreviate 1st letter uppercase 2nd letter lowercase Atomic Nucleus Contains protons and neutrons Contains most of atoms mass Protons Determines the element Positively charged Mass = 1 amu (atomic mass unit) 6 x 1023 amu = 1 gram Atomic number tells the number of protons in the atom Neutrons Neutral charge Mass about the same as proton – 1 amu Electrons Negatively charged Located outside nucleus in electron cloud Mass = 1/1836 amu Ions Charged atoms In neutral atoms, number of protons and electrons are equal so they have a 0 net charge In a 2+ ion, the atom has two less electrons than protons to give a positive 2 net charge Isotopes Atoms of the same element that contain different numbers of neutrons Mass number Total number of protons and neutrons in an atom Atomic mass Average mass of all isotopes of that element Found on periodic table # neutrons = Mass number – atomic number Row on the periodic table is called Period Column on the periodic table is called Group or family Group or Family names Diagram of atom Atoms are mostly empty space Nucleus is 1/10000 of the size of the whole atom Bohr Model Diagrams Simplified energy levels using Bohr’s idea of circular orbits. Lithium Atomic #: 3 Mass: 7 # of p: # of e: # of n: 3 3 4 eep n n n p p n e- Can replace with: 3p 4n Maximum eLevel 1 2eLevel 2 8eLevel 3 18eLevel 4 32e- Bohr Models Periodic Trend Things that occur in a repeating pattern on the periodic table Atomic number, # of energy levels, valence electrons, oxidation #, atomic size, metallic properties Physical properties of metals Malleable – can be hammered into a thin sheet Ductile – can be pulled into thin wire High density Solid at room temperature Good conductors of heat and electricity Luster - shiny Physical properties of nonmetals Brittle Low density Low melting point Solid, liquid, or gas at room temperature Poor conductors of heat and electricity dull Oops! Those "harmless" germanium capsules you just swallowed may have an extra proton in each nucleus. Is this good news or bad news? Why? Which has more atoms: A one gram sample of carbon-12, or a one gram sample of carbon-13? Suppose you could add or subtract protons from oxygen nuclei. To turn oxygen into a gas that would glow red when an electric current flows through it, would you add or subtract protons? How many? Compared to hydrogen, the element helium has a) more mass and is larger in size b) more mass and is about the same in size c) more mass and is smaller in size d) none of the above