Chapter 1 Chemistry: The Science of Matter Section 1: The Puzzle of Matter

The Puzzle of Matter: Learning Objectives Classify matter according to its composition Distinguish among elements, compounds, homogeneous mixtures, and heterogeneous mixtures Relate the properties of matter to structure

A picture of Matter Composition and Behavior Chemistry Matter Mass Examples of things that are not matter: Heat and light from a lamp Thoughts Ideas Radio waves Magnetic fields

A picture of Matter cont.. Composition and Behavior Structure of matter refers to its composition (what matter is made of) Also organized Properties Includes the changes that matter undergoes Figure 1.2 Discussion

A picture of Matter Composition and Behavior You can determine some properties of matter by examining and manipulating matter. Figure 1.3 You usually cannot tell what something is made up of only by looking at it. Measurements must be made or chemical changes observed. Figure 1.4

A picture of Matter The macroscopic level of matter Matter that is large enough to be seen is called macroscopic Touch, feel, smell, taste, and see. Figure 1.5 The appearance and properties of a piece of matter are a direct result of its structure. Submicroscopic view

A picture of Matter The submicroscopic level of matter Talking about atoms Scanning Tunneling microscope produces images on a computer of atom location

Using Models in Chemistry Chemistry uses both macroscopic and submicroscopic perspectives Sucrose and aspirin are composed of same elements: Hydrogen, Carbon, and Oxygen. The differences in these substances are related to the number of atoms and the microscopic arrangement of their atoms Figure 1.7 Use an analogy

Using Models in Chemistry Different Types of Models Models are sometimes something you can see and manipulate Models we are familiar with—model cars, airplanes, proposed buildings A model of a submicroscopic structure of matter must explain the observed macroscopic behavior, and predict behavior not yet observed. Figure 1.8 gives example of a Scientific Model Data from many experiments are gathered to create a visual, verbal, or mathematical model.

Classifying Matter Classification by composition Broadest type of classification What is it made of ? Sucrose – elements carbon, hydrogen, and oxygen This description is a qualitative observation. How much of each is present? 100.0 g of sucrose- 42.1g of carbon, 51.4g of oxygen, 6.5g of hydrogen This is a quantitative observation.

Classifying Matter Pure Substance or a mixture? Pure Substances Every bit of matter being examined is the same substance Composition is fixed White sand (silicon dioxide)- 53.2 % oxygen, 46.8% silicon Mixtures Every particle is not the same So the properties are not the same throughout. Composition is also not fixed Discussion-Pure Substance, Mixtures Tie to previous Knowledge

Classifying Matter Pure Substance or a mixture? Most of matter you encounter everyday is a mixture. Figure 1.12 Mixtures Everyday Chemistry

Classifying Matter The separation of mixtures into substances Mixtures can be separated into its components by physical processes. The word physical tells you that the process does not change the identity of a substance Separating by physical change in one easier way to separate mixtures Boiling, freezing, melting, evaporating, dissolving, and crystallizing. Physical Properties Solubility, melting point, boiling point, color, density, electrical conductivity, and physical state (solid, liquid, or gas) Figure 1.13 Demo-suspensions and colloids

Classifying Matter Types of Mixtures Heterogeneous mixtures are ones that do not have a uniform composition and in which the individual substances remain distinct. “hetero”-different “genea”-source Homogenous mixtures are the same throughout. Sugar in water, lemonade, ect. “homo”-same Another name for a homogenous mixture is solution.

Classifying Matter Types of mixtures Liquid solutions do not have to contain water Gasoline, air, steel Alloys Table 1.1 Aqueous solution-when solvent is water When you dissolve sugar in water, sugar is the solute The water is the solvent Soft drinks, tea, contact-lens cleaner, and other cleaning liquids Most processes of life!!!

Substances: Pure Matter Elements: The Building Blocks There are two types of pure substances Compound Can be broken down to simpler substances Element Type of substance that cannot be broken down into simpler substances Only 117 elements that combine with each other to form the millions of known compounds Only 92 occur naturally in Earth Less than half are abundant enough to play a significant role in the chemistry of everyday life. All substances of the universe are elements, compounds formed from elements, or mixtures of elements and compounds. Literature Connection (Jules Verne and His Icebergs) Table 1.2

Substances: Pure Matter Compounds A more complete definition of compound is a chemical combination of two or more different elements joined together in a fixed proportion. Water is always 11.2 percent hydrogen and 88.8 percent oxygen by mass 2 hydrogen, 1 oxygen by atoms Every Compound has its own fixed composition, and that composituion results in a unique set of chemical and phusical properties. The properties of the compound are different the the individual elements properties that make up the compound. NaCl (table salt) Figure 1.18

Substances: Pure Substances Compounds Chemistry & Society Table 1.3 Common Compounds New compounds are discovered and isolated from natural sources such as plants and colonies of bacteria Also can be synthesized in laboratories.

Substances: Pure Substances Formulas of Compounds A chemical formula is a combination of the chemical symbols that show what elements make up a compound and the number of atoms of each element C12H22O11- 12 carbons, 22 hydrogen, 11 oxygen atoms Formulas provide a shorthand way of describing a submicroscopic view of a compound. Section 1.1 Assessment Writing about chemistry Detailed response to “Natural products are always better than synthetic products”