What is matter? Matter is…. Anything that takes up space (volume) and has mass. WaterRocks AirWood PlasticPeople
How is matter classified? One way that scientists classify matter is by its composition (what it is made of). Ultimately, all matter can be classified as elements, compounds and mixtures Elements and compounds are pure substances Mixtures are not pure substance
What are Pure Substances? A sample of matter that has a definite composition and definite chemical and physical properties
What are Elements? Made of one type of atom Cannot be separated into simpler substance by physical or chemical means. Located on the periodic table
What are atoms? The smallest part of an element Atoms are the basic building blocks of all matter molecules Atoms chemically joined together are called molecules
How are elements represented? Elements have names and chemical symbols of either 1 or 2 letters HHe Hydrogen Helium Some are natural and some are synthetic (man made) Currently there are about 109 known elements
What are Compounds? Are made of 2 or more atoms of different elements that are bonded together Made of elements in a specific ratio that is always the same Has a chemical formula Can only be separated by chemical means, not physically
What are Mixtures? A combination of two or more pure substances that are not chemically combined. substances held together by physical forces, not chemical No chemical change takes place Has a random composition Each item retains its properties in the mixture They can be separated physically Chem4kids.com
Is it uniform throughout? Matter is also classified by its uniformity If the answer is no, the matter is a heterogeneous mixture. Considered the “least mixed.” Does not appear to be the same throughout. Particles are large enough to be seen and to be separated from the mixture.
Is it uniform throughout? If the answer is yes, the matter is homogeneous (looks the same throughout). If it can be physically separated it’s a homogeneous mixture If it can not be separated then it is a pure substance –element or compound
Mixtures vs. Compounds http://www.bbc.co.uk/schools/ks3bitesize/science/chemistry/elements_com_mix_6.shtml
Can you identify the following? You will be shown a series of photos. Tell if each photo represents an item composed of an element, compound, or mixture. Review: An element contains just one type of atom. A compound contains two or more different atoms joined together. A mixture contains two or more different substances that are only physically joined together, not chemically. A mixture can contain both elements and compounds.