Compounds And Elements

Matter: anything that takes up space & has a mass Ex. a desk Ex. pizza Ex. silver necklace Ex. oxygen

Hetero-geneous Mixture Classification: Everything in the world that has a mass is called “matter” Matter can be classified as: Matter Pure Substance Mixture Element Ex. gold Compound Ex. water Hetero-geneous Mixture Homo-geneous Mixture

Pure Substance: Mixture: composed of a single substance with the same properties throughout Ex. water Ex. table salt Mixture: combinations of two or more substances that are not chemically combined (mixed) Easily separated Ex. fruit salad Ex. sugar in coffee

A pure substance can be further broken down into an element or a compound…… Elements: simplest form of matter cannot be separated or broken down into simpler substance Ex. Oxygen Ex. Aluminum Ex. Gold Ex. Copper

Recall, a pure substance can be further broken down into an element or a compound Compounds: substance made of two or more elements can be separated into simpler substance Ex. Water (H2O) Ex. Carbon dioxide (CO2) Ex. Sugar (C6H12O6) Ex. Salt (NaCl)

Element Compound Ex. oxygen & hydrogen Ex. water (H2O) NOTE: With chemical reactions you can go from an element to compound & vise versa!!! Element Compound Ex. oxygen & hydrogen Ex. water (H2O) O O H H H H

State whether the following are examples of an element or a compound. A gold ring element Rust (Fe2O3) compound Carbon monoxide (CO) compound Aluminum Foil element element Calcium

Ex #2 State whether the following are examples of an element or a compound or a mixture A blueberry muffin mixture Chunky Soup mixture Salt (NaCl) compound Helium element compound Water (H2O)

Ex #3 State whether the following pictures represent an element or a compound or a mixture Compound Compound Element Mixture

Which statement best describes a compound. Ex #4 Which statement best describes a compound. A) A pure substance that has a high melting point. B) A mixture that is formed by two or more elements. C ) A pure substance that is formed by two or more elements.

The Molecule Individual atoms can combine to form molecules. A molecule is a group of two or more chemically bonded atoms. A molecule is the smallest unit of a compound. Eg: H2O, CO2, C6H12O6

Molecules: Why? Recall elements can combine to form compounds But when atoms combine, they do so in specific ratios For example: Water, H2O Combines 2 Hydrogens for every 1 Oxygen Why?

This is called the Octet Rule Molecules: An atom wants to be stable To be stable, an atom must have a full outer electron shell (8 electrons) This is called the Octet Rule Atoms combine together, forming bonds, to fill their outer electron shell

Atoms combine to obtain a complete outer electron shell (8 valence electrons) Metals tend to lose electrons to achieve this and non-metals tend to gain electrons

IA IIA IIIA IVA VA VIA VIIA VIIIA Li Be B C N O F Ne 1 2 3 4 5 6 7 8 Group Number IA IIA IIIA IVA VA VIA VIIA VIIIA Example Li Be B C N O F Ne Valence electrons 1 2 3 4 5 6 7 8 Tendency Lose 1e- Lose 2e- Lose 3e- Gain or lose 4e- Gain 3e- Gain 2e- Gain 1e- None (stable)