Presentation on theme: "Physical Science: Ch 5 Notes"— Presentation transcript:
1 Physical Science: Ch 5 Notes A. Organizing the ElementsDmitri Mendeleev was a Russian chemist and teacher who organized the elements in the 1860s.Periodic table – an arrangement of elements in columns, based on a set of properties that repeat from row to rowPeriod: each row in the table of elements is a different periodGroup: each column on the periodic table is a different groupAtomic mass units (amu) – the units used to report atomic masses since the mass of an atom is so small in gramsAtomic Mass = the sum of protons and neutrons in an atom
2 Physical Science: Ch 5 Notes B. Classifying the Elements1. Classify by state of matter (at room temperature)Liquids: Mercury and BromineGases: Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine, Helium, Neon, Argon, Krypton, Xenon, RadonSolids: all the rest!2. Classify by general propertiesMetals: majority of elements (left side and middle of periodic table)Metalloids: Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium, Polonium, AstatineNonmetals: Elements at the top, right of the periodic table and Hydrogen
3 Physical Science: Ch 5 Notes classifying continued…3. Elements can also be divided into those that occur naturally and those that do notElements with atomic numbers 43 and 61 do not occur naturallyElements with atomic numbers 93 and above are also not naturally occurring.C. Element CharacteristicsMetals – elements that are good conductors of electric current and heat (malleable and shiny too!)Ductile – can be drawn into thin wiresNonmetals – elements that are poor conductors of heat and electric current (most are gases, some are dull, brittle solids)Metalloids – elements with properties that fall between those of metals and nonmetals
4 Physical Science: Ch 5 Notes D. Electron TrendsValence electron – an electron that is in the highest occupied energy level of an atomThese electrons play a key role in chemical reactions – atoms want to have a full outer energy level so they will gain or lose electrons to make this happenProperties vary across a period because the number of valence electrons increases from left to rightElements in a group have similar properties because they have the same number of valence electrons.