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Learn how to determine if something is an element through its properties and placement on the periodic table. Understand the characteristics of metals, nonmetals, and metalloids. Explore compounds and their differences from elements. Discover the classification and separation methods of mixtures.
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ELEMENTS, COMPOUNDS, & MIXTURES
How can you determine whether something is an element or not? They are all listed on the periodic table. ELEMENT SONG
ELEMENTS • Pure substance • Made of only 1 type of particle • Ex: copper wire only has copper atoms • Can’t be separated into simpler substances by chemical or physical means
ELEMENTS • Each has a unique set of properties • Called characteristic properties • Can be physical or chemical • Classified by their properties • Metals • Nonmetals • Metalloids melting pt. reactivity density flammability Elements Metalloids Metals Nonmetals
Develop the concept map by adding info. about metals, nonmetals, & metalloids METALLOIDS • Characteristics of metals and nonmetals • Semiconductors • Ex: silicon, germanium METALS • Shiny • Good conductors • Malleable • Ductile • Ex: gold, silver, copper NONMETALS • Dull (no shine) • Poor conductors • At room temp, only a few are solids that are brittle • Most are gases • Ex: hydrogen, oxygen, helium
COMPOUNDS • Do you know any compounds? • How are they different from elements? • Characteristics • Found in nature more often than pure elements • Have more than one element • Elements are chemically bonded to each other • Mg + O2 makes MgO • Pure substances that occur in fixed ratios by mass • 1g H to 8g of O in every water molecule • Can’t be separated by physical means • Have their own unique set of properties
Mixtures • 2 or more substances that are not chemically bonded • So diff parts keep their own properties • Ex: • pizza • granite • Kool-aid • Brass • Jello • Parts do not occur in a definite ratio • Compare the 2 pepperoni pizzas
Mixtures • Can be physically separated by • Distillation • Magnet • Centrifuge • Filtration • Evaporation
Mixtures • Can be heterogeneous (see diff pieces) or homogeneous (uniform appearance) • Homogeneous mixtures are called solutions • Heterogeneous mixtures include suspensions • Colloids are classified as heterogeneous in some books and homogeneous in others
Solutions – look the same throughout • From Chem4kids • How much solute can dissolve in water? • Solubility graph can tell you • Most compounds show a(n) ________ in solubility as temp. inc. • Which compound shows the greatest increase in solubility as temp inc? • Which compound(s) actually dec in solubility as temp inc.? • How much potassium nitrate will dissolve in 100 ml of water at 40oC? • How much sodium nitrate will dissolve in 100 ml of water at 90oC?
Solubility Graph • Which compound shows the greatest increase in solubility as temp inc? • Which compound(s) actually decrease in solubility as temp inc.? • Which compound has the highest solubility at 58oC?
Fill-in the Venn diagram with characteristics. SOLUTION COLLOID SUSPENSION
SOLUTION • Ex: Kool-aid, salt water, brass • Don’t scatter light/ light passes right thru • Smallest solute particles • Do not settle out • Pass thru filter paper Can pour some • mixtures • Settle out on standing • Separate w/filter paper • Largest particle size (seen) • Ex: blood, muddy water, Italian salad dressing COLLOID • Medium particle size • Don’t easily pour • Ex: Jell-o, fog, milk, mayo, whipped cream • Scatter light SUSPENSION