Warm-Up: 2/4 Classifying Elements Head a sheet of paper and title it: Elements, Compounds, and Mixtures Notes Science Binder page 32 Make a subheading (smaller title under the main title) – Warm-Up: 2/3 Classifying Elements Write a short paragraph explaining what makes something an element. Include examples.

Elements, Compounds and Mixtures Notes Science Binder p. 32

Classification of Substances Elements Molecules Compounds Mixtures

Elements Elements are substances made up of only one type of atom. Example  Hydrogen, Gold.

Elements Pure substance that cannot be separated into simpler substances by physical or chemical means. Pure substance- a substance in which there is only one type of particle (atom or molecule)

Periodic Table of Elements

Molecule A molecule is made up of two or more atoms chemically bonded. Atoms can be the same or different!

Compounds Compounds are pure substances made up of two or more different types of atoms chemically bonded.

Properties of Compounds When a compound is formed during a chemical reaction its properties differ from those of the elements it is made of. Example: Water is made from hydrogen and oxygen. Hydrogen  flammable gas Oxygen  colorless gas.

Compounds Represented by chemical formulas with two or more chemical symbols (each capital letter = a new chemical symbol/element) NaCl = sodium chloride (table salt) H2O2 = hydrogen peroxide C6H12O6 = glucose (sugar plants make from photosynthesis)

Chemical Formulas subscript- small number located at the bottom right of a chemical symbol, and gives the number of atoms for the element in that molecule

Mixtures A mixture consists of two or more different substances mingled together but not chemically combined. Examples: Sea – water and salt Air – nitrogen, oxygen … Soil – sand, clay, humus …

Compare mixtures and Compounds.

Mixture Compound The amounts of the substances in the mixture can vary. The elements in a compound are always present in the same fixed proportion. A mixture contains two or more substances A compound is a single substance. The properties of a mixture are similar to those of the substances in a mixture. The properties of a compound are different to those of the elements which reacted to form it. There are practically no energy changes when a mixture is made Heat is usually given out or taken in when a compound is formed. It is usually easy to separate the components of a mixture. It is usually difficult to separate the components of a compound.

iron particles Key: one iron particle strong bonds between iron particles iron particles held together by strong bonds

iron particles iron particles are attracted to a magnet iron particles diagram

sulfur particles Key: one sulfur particle strong bonds between sulfur particles sulfur particles held together by strong bonds

sulfur particles sulfur particles are not attracted to a magnet sulfur particles diagram

iron particles sulfur particles

A mixture of iron and sulfur particles What’s this? A mixture of iron and sulfur particles strong bonds between iron particles strong bonds between sulfur particles

A mixture of iron and sulfur particles A magnet attracts the iron particles but not the sulfur particles. The mixture is separated mixture diagram

A compound between iron and sulfur particles What’s this? A compound between iron and sulfur particles one iron particle one sulfur particle strong bonds between iron and sulfur particles

A compound between iron and sulfur particles strong bonds between iron and sulfur particles The magnet cannot separate iron and sulfur particles in a compound compound diagram

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