The science of chemistry Chapter 1 The science of chemistry

1-1 What is Chemistry? Chemical is any substance with a definite composition. Can you come up with any examples? Misconception: That chemicals differ from substances and materials in nature.

1-1 What is Chemistry? What forms do chemicals come in? Physical state – arrangement of particles in matter.

1-1 What is Chemistry? Chemical Reaction – elements and/or compounds rearrange to form new compounds

1-1 What is Chemistry? Chemical reactions are classified by energy being given off or absorbed during the process. Exothermic reaction - energy is given off during the reaction (energy is released as bonds are broken) Endothermic reaction – energy is absorbed during the reaction (more energy is needed to break bonds than to form the bonds on the product side)

1-2 What is matter? It is important to have a good definition of matter when studying chemistry ……because chemistry is the study of matter and how it interacts. Matter is anything that has mass and volume Mass – quantity of matter in an object (expressed in grams or kilograms and use a balance to measure it) Volume – amount of space an object occupies (expressed in L, mL or dm3 and use a graduated cylinder to measure liquids) What is the difference between mass and weight?

1-2 What is matter? Qualitative vs Quantitative measurement

1-2 What is matter? What can we measure and how can we measure it?

Problem Solving and Dimensional Analysis 1-2 What is matter? Problem Solving and Dimensional Analysis Find the equality between the two units Make a conversion factor (relates two units of measure and is a way to change from one unit to another.) Multiply given quantity by the conversion factor so the original unit cancels out

1-2 What is matter? Metric system is a system of measure based on units of 10 and is used by scientists.

1-2 What is matter? Derived units – created from a combination of base units. Volume of a regular solid = L x W x H Density = mass/volume Rate of speed = distance / time

1-2 What is matter? Physical Property – describes measurable, physical attributes of the substance Ex. Density, odor, color, melting point, boiling point Chemical Property – refers to the ability of substances to forms new substances Ex. Flammable, toxic, inert

1-2 What is matter? Physical Change generally a phase change (substance will still have same chemical formula)

1-2 What is matter? Indicators of a Chemical Change Color change Gas is produced Energy is released or absorbed Precipitate is formed Chemical Change bonds between atoms are broken and new bonds are firmed to create new substances with new chem/phys properties

1-3 What is the nature of matter? Compounds – formed by 2 or more elements being bonded chemically Elements – composed of only one type of atom

1-3 What is the nature of matter? Some elements have allotropic forms. It is due to the way it is bonded and the number of atoms present.

Classification of Matter