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Science 9 Chapter 2.2. The periodic table. Today. Elements ( more tomorrow) Chemical symbols The periodic table Mendeleev Families Workbook pages for homework Coming up… learning about elements. Elements. A pure substance that cannot be broken down or separated into simpler substances
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Science 9 Chapter 2.2 The periodic table
Today • Elements (more tomorrow) • Chemical symbols • The periodic table • Mendeleev • Families • Workbook pages for homework Coming up… learning about elements
Elements • A pure substance that cannot be broken down or separated into simpler substances • Made up of one kind of atom • There are currently 118 known elements http://images-of-elements.com/
Chemical symbols • Consist of 1 or 2 letters • E.g., • H = Hydrogen • Mg = Magnesium • Na = Sodium (Latin = natrium)
Elements can be metals, non-metals, or metalloids Metal properties: • Shiny • Usually solid • Malleable (hammer or press without cracking) • Ductile (stretch into thin wire) • Good conductors of heat and electricity
Carbon Non-metals • Dull • Gases or brittle solids • Non-malleable and non-ductile • Poor conductors of heat and electricity Chlorine gas
Metalloids: properties of both metals and non-metals • Solids • Shiny or dull • May conduct electricity • Poor conductors of heat • Non-malleable and non-ductile Selenium Silicon
The Periodic Table • Organizes elements by their physical and chemical properties • Developed by Dmitri Mendeleev in 1867
Mendeleev • Organized known elements by properties and characteristics • Recognized the need to leave spaces for elements not yet discovered
The periodic table • Includes the element’s name, symbol, atomic number, atomic mass, and ion charge
The periodic table • Periods = horizontal rows • Families = vertical columns • Elements in the same family have similar physical and chemical properties.
Today • HW check wb 28-29 • Video • Periodic table • Mendeleev • Families! • Due Monday: wb 30-31 and Periodic Table Coming up… learning about elements
Alkali Metals • http://www.youtube.com/watch?v=m55kgyApYrY
Alkali Metals (family #1) • HIGHLY reactive with halogens • Reactive with oxygen and water • Low melting points • Soft
Alkaline earth metals (family #2) • Less reactive than alkali metals • Burn in air if heated • Produce bright flames • React with water
Halogens (family #17) • Non-metals • Highly reactive
Nobel Gases(family #18) • Very stable • Un-reactive • All gases
Transition Metals • Found at the centre of the periodic table • Complex arrangement of electrons • Fe, Co, and Ni are magnetic
Today • Elements • Chemical symbols • The periodic table • Mendeleev • Families • Workbook pages due tomorrow: 28-31 Coming up… learning about elements http://www.youtube.com/watch?v=zGM-wSKFBpo