Substances, Mixtures and Elements

POINT > Contrast substances and mixtures POINT > Distinguish homogeneous and heterogeneous mixtures POINT > Introduce organization of the Periodic Table POINT > Distinguish metals, nonmetals, and metalloids

POINT > Contrast substances and mixtures All matter can be classified as either a pure substance or a mixture The composition of a substance does not change within a sample or between samples A pure substance can be an element or a compound (nitrogen, silver, water, glucose, butane) If the substance is a compound, it can be broken down chemically into its elements (water  hydrogen + oxygen)

POINT > Contrast substances and mixtures The composition of a mixture can differ between samples, or within a sample Mixtures contain two or more substances (salt water, air, orange juice, granite, steel) A mixture can be separated physically into its component substances

POINT > Contrast substances and mixtures A mixture can be separated physically into its component substances: Ex. Filtration separates solids from a liquid Distillation separates two liquids Centrifugation and chromatography are other methods of physical separation

WB CHECK: Identify the following as a substance or a mixture: sucrose milk concrete gummy bear

POINT > Distinguish homogeneous and heterogeneous mixtures A homogeneous mixture has a uniform composition (glass, salt water, air, steel)

POINT > Distinguish homogeneous and heterogeneous mixtures A heterogeneous mixture has a non-uniform composition (granite, orange juice, concrete) Not always clear…

WB CHECK: Identify the following as homogeneous or heterogeneous mixtures: gravel gummy bear Lucky Charms

Matter SubstanceMixture ElementCompound Homogeneous Mixture Heterogeneous Mixture Can be Separated Physically Can be Separated Chemically

POINT > Introduce organization of the Periodic Table The Periodic Table organizes elements by their chemical properties (more on this later) The vertical columns are called Groups, and they are numbered* The elements in a group have similar chemical properties

POINT > Introduce the Periodic Table organization The horizontal rows are called Periods Chemical properties change across a Period Elements close to each other in a Period are more similar in chemical properties. Those far apart are very different.

POINT > Distinguish metals, nonmetals, and metalloids Most of the elements are metals. Metals are characterized by being good conductors of electricity. Most metals are shiny or have luster. Metals are solid at room temperature (except Hg)

POINT > Distinguish metals, nonmetals, and metalloids Nonmetals are poor conductors of electricity. Many nonmetals are gases at room temperature (oxygen, nitrogen, helium, etc) Nonmetals are in the upper right of the Table

POINT > Distinguish metals, nonmetals, and metalloids Metalloids are semiconductors, and have characteristics of both metals and nonmetals. They are found between metals and nonmetals on the Periodic Table

WB CHECK: Find strontium (Sr) on the Periodic Table. Which Group does Sr belong to? Which Period does silver (Ag) belong to? Do you expect calcium (Ca) to be a good conductor? Is sulfur (S) a metal or nonmetal?

Be ready Thursday for a Quiz on anything we’ve covered!