What is Matter? Chapter 2.1

Goals Explain the relationship between matter, atoms, and elements Distinguish between elements and compounds Describe molecules and how they are formed Interpret and write some common chemical formulas Categorize materials as pure substances or mixtures

What is Chemistry?? Chemistry is…“the study of matter and its changes” So what is matter?? Anything that has mass and takes up space!

Matter quiz! Is a doorknob matter? Is a shadow matter? Yes! Is a shadow matter? No. Is a laugh matter? Is a pencil matter? Is an atom matter?

What is an element?? A substance that cannot be separated or broken down into simpler substance by chemical means (Check out the Periodic Table of Elements!) You cannot break down carbon, oxygen, etc. into any other element or compound Name some other elements…

What is an atom? The smallest unit of an element that maintains the properties of that element Ex: An atom of carbon Atoms have distinct properties specific to the element they represent Atoms are composed of protons, neutrons, and electrons

Building up to…Compounds A substance made of atoms of 2 or more different elements that are chemically combined Ex: Nylon What kinds of atoms do you think nylon is made of? Carbon, hydrogen, nitrogen, and oxygen

On a separate piece of paper…create 2 pie charts… Label and fill in the percentages of what you think the human body is composed of… Include nitrogen, sulfur, carbon, oxygen, potassium, calcium, phosphorus Label and fill in the percentages of what you think the Earth as a whole is composed of… Include oxygen, nickel, magnesium, sulfur, silicon, iron, and calcium

So what’s a molecule? Atoms combine and act as a unit, known as a molecule The smallest unit of a substance that keeps all of the physical and chemical properties of that substance. So if you pull apart one molecule of a substance, it will have the same properties of a bunch of molecules combined Example: H2O (the atoms combine and act as one water molecule unit)

Molecules Molecules may be combinations of atoms of the same element or different elements So…H2O is a molecule, but so is O2 How do you represent a molecule of table salt? NaCl (Sodium chloride)

Chemical Formulas A combination of chemical symbols and numbers to represent a substance What is the chemical formula for water? What is the chemical formula for salt? What is the chemical formula for sugar (glucose)? How many atoms are present in each of the substances above?

Pure Substances vs. Mixtures Pure substances  a sample of matter (either a single element or a single compound) that has definite chemical and physical properties Example: Water Mixture  a combination of two or more substances that are not chemically combined Example: Oil and Water Example: Cereal and Milk

Classifying Mixtures Heterogeneous—mixtures that are not evenly distributed (“hetero” = different) Example: Flour in Water, Sandy Water, Chicken Noodle Soup Homogeneous –mixtures that are evenly distributed (“homo” = same) You cannot see the separate parts of a homogeneous mixture Examples: Blood, Sugar Water, Salt Water, Gasoline

…Classifying Liquid Mixtures… Miscible  a mixture that “totally mixes” the parts dissolve into each other and the mixture does not separate Miscible liquids form homogeneous solutions Example: Ethanol and Water, Salt and Water Immiscible  a mixture where the parts do not dissolve into one another The parts will separate with time Example: Oil and Water

Gases can also mix with liquids… Examples? Carbonated beverages Are these homogenous or heterogeneous mixtures? Lemon meringue pie Lava Pumice rocks