Ch. 1--What Is Chemistry?

Ch. 1--What Is Chemistry? • 1.1—Chemistry is a Physical Science • 1.2—Matter and Its Properties • 1.3—Elements

1.1- Chemistry is a physical science Chemistry is the study of the composition of matter and the changes that matter undergoes. Matter is anything that has mass and occupies space. Why is the scope of chemistry so vast? Because living and nonliving things are made of matter, chemistry affects all aspects of life and most natural events.

1.1 Areas of Study There are many areas of study in chemistry. Some topics have specific names while others are generalizations. • We will specifically cover organic and nuclear chemistry • Most everything we talk about outside of the organic chapter is considered inorganic chemistry • When we look at the components and composition of materials it is considered analytical chemistry • Thermochemistry is a large part of the broad category of physical chemistry

1.1 Why Study Chemistry? • Chemistry can help you satisfy your natural desire to understand how things work. Chemistry can be useful in explaining the natural world, preparing people for career opportunities, and producing informed citizens. Pure research can lead directly to an application, but an application can exist before research is done to explain how it works. • Pure chemistry is the pursuit of chemical knowledge for its own sake (basic research). • Applied chemistry is research that is directed toward a practical goal or application (applied research).

1.1 Pure and Applied Chemistry • Aspirin • Long before researchers figured out how aspirin works, people used it to relieve pain, and doctors prescribed it for patients who were at risk for a heart attack. (ex. Hippocrates (400 B.C.) left historical records of pain relief treatments, including the use of powder made from the bark and leaves of the willow tree to help heal headaches, pains and fevers.) • In 1971, it was discovered that aspirin can block the production of a group of chemicals that cause pain and lead to the formation of blood clots. This is an example of pure research. Nylon • In the early 1930’s, Wallace Carothers produced nylon while researching cotton and silk. • A team of scientists and engineers applied Carothers’s research to the commercial production of nylon.

1.1 Pure and Applied Chemistry Technology is the means by which a society provides its members with those things needed and desired. • Technology allows humans to do some things more quickly or with less effort. • There are debates about the risks and benefits of technology.

1.3 Alchemy before Chemistry Early chemistry is called alchemy. Alchemists developed the tools and techniques for working with chemicals. Chemistry is a systematic method of study of matter. Alchemists developed processes for separating mixtures and purifying chemicals. They designed equipment that is still in use today including beakers, flasks, tongs, funnels, and the mortar and pestle. • Antoine-Laurent Lavoisier (late 1700’s) • Lavoisier helped to transform chemistry from a science of observation to the science of measurement that it is today. • He designed a balance that could measure mass to the nearest 0.0005 gram. He also showed that oxygen is required for a material to burn. Mortar and Pestle

1.2- Matter and its properties • Mass is a measure of the amount of matter • Basic Building Block of Matter The fundamental building blocks of matter are atoms and molecules. An atom is the smallest unit of matter that has the properties of that matter. An element is a pure substance made of only one kind of atom. Ex. hydrogen, oxygen. A compound is a substance that is made from the atoms of two or more elements that are chemically bonded.

Properties of Matter • Properties can help reveal the identity of an unknown substance. Usually one needs to determine more than one property of the substance to identify it.. There are two types of properties: extensive and intensive. • Extensive properties depend on the amount of matter present such as mass or volume. • Intensive properties are independent of the amount of substance such as melting point, boiling point, or density.

2.1 States of Matter • Three states of matter are solid, liquid, and gas. • A solid is a form of matter that has a definite shape and volume. • A liquid is a form of matter that has an indefinite shape, flows, yet has a fixed volume. • A gas is a form of matter that takes both the shape and volume of its container. • Vapor describes the gaseous state of a substance that is generally a liquid or solid at room temperature, as in water vapor.

Matter exists in three states. • Solid: A solid is rigid and has fixed volume and shape. Ex. ice, book, pencil, etc. • Liquid : A liquid has a definite volume but no definite shape. It takes the shape of its container. Ex. water, oil, wine, etc. • Gas: A gas has no definite volume or shape. It takes on the shape and volume of its container. Ex. steam, air, hydrogen, etc.

physical and chemical properties • Physical Property: • The physical properties of matter include what we see when we look at an object such as the color or state of the object (solid, liquid, gas). A physical property is a characteristic that can be observed without changing the identity of the substance. • A change in the substance that does not involve the change in the identity of the substance is called a physical change. Common physical changes are the changes of state (such as water freezing from liquid to solid, or boiling where the water changes from liquid to gas state), hardness, color, conductivity, and malleability. • As gallium melts in a person’s hand, the shape of the sample changes, but the composition of the material does not change.

physical and chemical properties • Chemical Property: • The chemical properties of matter are what we see or what we get when matter interacts with other matter, such as when we mix 2 liquids. We can only observe chemical properties, or changes in chemical properties by interacting substances with each other. The chemical property is a substance’s ability to undergo changes that will transform it into a new substance. A change in which one or substances are converted into different substances is called a chemical change. The chemical changes are generally referred to as chemical reactions in which the beginning substances are called reactants and the ending substances are called products. • Ex. of chemical reactions are rusting of iron, burning of wood, etc.

2.4 Chemical Changes • A mixture of iron and sulfur is heated. The iron and sulfur react and form iron sulfide. This is an example of a chemical change. A magnet separates iron from sulfur. This is an example of a physical change. • A chemical change is also called a chemical reaction. • One or more substances change into one or more new substances during a chemical reaction.

2.4 Recognizing Chemical Changes Possible clues to chemical change include: • a. a transfer of energyb. a change in colorc. the production of a gasd. the formation of a precipitate c: cheese (milk curds and liquid whey) • A precipitate is a solid that forms and settles out of a liquid mixture. • Clues to chemical changes have practical applications.

2.2 Classifying Mixtures • A mixture has a variable composition. • Ex. wood, wine, air. Mixtures can be of two types: • A pure substance will always have the same composition. Pure substances are either elements or compounds. • Elements: Elements are substances that cannot decomposed into simpler substances by chemical or physical means. Ex. carbon, oxygen. • Compounds: A compound can be broken down into elements by chemical means. Ex. water, ozone, carbon dioxide. • When physical or chemical changes occur, energy is almost always involved. The energy can take several different forms such as heat or light. Energy can be absorbed or released

2.2 Classifying Mixtures Based on the distribution of their components, mixtures can be classified as heterogeneous mixtures or as homogeneous mixtures. A mixture in which the composition is not uniform throughout is a heterogeneous mixture. A mixture in which the composition is uniform throughout is a homogeneous mixture. Another name for a homogeneous mixture is a solution.

2.2 Classifying Mixtures The term phase is used to describe any part of a sample with uniform composition and properties. • A homogenous mixture consists of a single phase. • A heterogeneous mixture consists of two or more phases. When oil and vinegar are mixed they form layers, or phases. The oil phase floats on the water phase.

Separation of Mixtures (Physical Methods of Separation) • All mixtures can be separated by exploiting some physical property. No chemical changes need to be involved, so the substances retain their chemical identity through the separation process. Chemists use various processes for separating different kinds of mixtures such as hand separation, filtration, using a separating funnel, distillation, centrifugation, or chromatography. • During a distillation, a liquid is boiled to produce a vapor that is then condensed into a liquid. • The process that separates a solid from the liquid in a heterogeneous mixture is called filtration. • A colander is used to separate pasta from the water in which it was cooked. This process is a type of filtration.

Separation of Compounds (Chemical Separation) • Chemical separation is used to break down a compound in its elements. Chemical means of separation are pretty harsh. One commonly employed method for chemical separation is “electrolysis”.

2.3 Distinguishing Substances and Mixtures If the composition of a material is fixed, the material is a substance. If the composition of a material may vary, the material is a mixture. Sodium chloride (table salt) is one atom of sodium for every one atom of chlorine (chloride) and, therefore, a substance (compound). Steel, however, is an alloy often made primarily of carbon and iron. There may be a different amount of iron atoms per carbon atom depending on the purpose of the steel and is, therefore, a mixture.

Distinguishing Substances and Mixtures

2.4 Conservation of Mass and Energy The law of conservation of mass states that in any physical change or chemical reaction, mass is conserved. During any chemical reaction, the mass of the products is always equal to the mass of the reactants. The conservation of mass is easily observed when a change occurs in a closed container. The law of conservation of energy states that in a physical or chemical reaction, energy is conserved. Energy may be released or absorbed in a reaction, but the amount of energy in the entire system (ex. Universe) remains the same.

1.3- Elements • Periodic Table of Elements Each small square in the periodic table contains one element. The horizontal rows are called as the periods. The vertical columns are called as groups, or families.

4.3 1.3- Elements A periodic table is an arrangement of elements in which the elements are separated into groups based on a set of repeating properties. A periodic table allows you to easily compare the properties of one element (or a group of elements) to another element (or group of elements). Each horizontal row of the periodic table is called a period. Within a given period, the properties of the elements vary as you move across it from element to element. Each vertical column of the periodic table is called a group, or family. Elements within a group have similar chemical and physical properties.

6.1 Metals, Nonmetals, and Metalloids • Metals, Metalloids, and Nonmetals in the Periodic Table

Ch. 1--What Is Chemistry?