Chapter 1 CHEMISTRY 1

All the physical stuff in our universe is called MATTER

What is NOT Matter?

Is Air Matter? What are the two criteria for matter? Does it take up space? Does it have mass?

Basic forms of matter on earth Microscopic views

WATER STATES OF MATTER Same for the cup of water as the iceberg

Are there more than 3 states of matter? Fermionic condensates

Substance

Substance Compound Element The purest or simplest form of a substance is an element There are 117 known elements 94 elements occur naturally Elements in compounds are combined in a definite ratio Pure substances containing more than one different element are known as compounds

ELEMENTS THAT EXIST AS DIATOMIC MOLECULES

Mixture A mixture consists of two or more different substances physically combined A good example of a mixture is a salad There are tomatoes, lettuce, cucumbers, radishes, etc, all mixed together You can separate each of the vegetables from each other

If the particles are spread evenly throughout the mixture but are not quite but almost visible, a colloidal suspension exists. Colloidal Suspension

Properties of matter Physical Properties Chemical Properties

Physical & Chemical Properties Intensive Properties Extensive Properties Intensive Properties do not depend on the amount of matter present. These properties are the same for a given substance regardless of how much of the substance is present. Density, chemical composition, temperature, flammability Extensive Properties depend upon the amount of matter that is present. Mass, volume, weight

Why is this important? Intensive properties can be used to identify a substance… extensive properties cannot

Physical Properties Characterize the physical state and physical behavior of a substance Each substance has unique physical properties Macroscopic Microscopic

“When we try to pick out anything by itself, we find it is tied to everything else in the universe” John Muir

Color Size Shape Density Odor Hardness Mass Texture

Chemical Properties Chemical properties describe the ability of a substance to change their composition

Changes in Matter Physical changes Chemical changes

Physical Matter Changes Matter only changes its physical appearance but not its composition E x a m p l e s Making an ice cube Sawing wood Crushing a Tablet Dissolving sugar in water

Changes in state of matter is a physical change Release energy Require input of energy or

Shock wave at the back of a plane is visible due to condensation of water vapor in the air

Chemical Matter Changes A chemical change is a reaction that transforms (changes) a substance into a new substance or substances with different properties. Match burning Explosion Rust

Observe the following amateur scientists testing matter and determine if it will undergo a physical or chemical change:

Is grilling causing a Chemical or Physical change to the meat?? Chemical !!

Is sunbathing causing a Chemical or Physical change to the skin? Chemical

Does eating & digestion cause a chemical or physical change to the food? Chemical

Is using a jackhammer making a chemical or physical change to the concrete? Physical

Is shooting a rocket Chemical or physical change? Chemical

Every field of knowledge has its own “language.” The “language” of science is mathematics

Many properties of matter are quantitative (associated with numbers) Science uses a select group of the metric system known as SI units

Even more amazing…. In fact, to help the SI units apply to a wide range of phenomena, the 19th General Conference on Weights and Measures in 1991 extended the list of metric prefixes so that it reaches from yotta- at 1024 (one septillion) to yocto- at 10-24 (one septillionth).

Mass : the measure of the amount of matter in a object SI unit: Kilogram

length SI unit: meter

Temperature SI unit: Kelvin However, most countries use the Celsius scale

Volume SI unit: m3 (cubic meter) Chemistry uses the liter Do you know how to read the Meniscus?

Density is a measure of the concentration of matter in an object Unit: g/cm3 or g/mL

Anything more dense than water will sink Anything less dense than water will float

Scientific Notation Scientists must often deal with extremely large or small numbers Scientific notation is a way of expressing very large or very small numbers which are awkward to say and write.

We need scientific notation for these numbers!

Writing a number in scientific notation: 1) Put the decimal after the first digit and drop the zeroes 2) Count the number of decimal places moved in step 1 3) Write as a product of the number (step 1) and 10 raised to the power of the count (step 2) The Andromeda Galaxy (the closest one to our Milky Way galaxy) contains at least 200,000,000,000 stars. So we would write 200,000,000,000 in scientific notation as: 2.0 x 1011 This number is read as follows: "two point zero times ten to the eleventh."

Now we try a number that is very small. Change 0.000000902 to scientific notation The decimal must be moved behind the 9 The coefficient will be 9.02 The decimal moves seven spaces to the right, making the exponent -7 Answer equals 9.02 x 10-7 

Examples Write each of the following numbers in scientific notation: (a) 93,000,000 (b) .00005144 (c) -33,452.8

Changing numbers from scientific notation to standard notation.       Change 6.03 x 107 to standard notation. we can simply move the decimal seven places to the right because the exponent is 7. So, 6.03 x 107 = 60 300 000

Now let us try one with a negative exponent. Ex.2 Change 5.3 x 10-4 to standard notation. The exponent tells us to move the decimal four places to the left. so, 5.3 x 10-4 = 0.00053

Express in standard form: 1.  1.09 x 103   2.  4.22715 x 108   3.  3.078 x 10-4   4.  9.004 x 10-2   5.  5.1874 x 102 (This can be tricky!)

Answers: 1) 1090 2) 422,715,000 3) 0.0003078 4) 0.09004 5) 518.74

Scientific certainty Precision Accuracy Accuracy indicates how close a measurement is to the accepted value. Precision indicates how close together or how repeatable the results are.  Accurate Inaccurate

Trial #1 #2 #3 #4 #5 Student A 14.8 14.1 14.5 14.6 14.2 Student B 14.8 14.2 14.6 14.5 14.8 Student C 14.6 14.5 14.5 14.4 14.6 PRECISION AND ACCURACY -- Quiz Consider the data obtained for the length of an object as measured by three students. The length is known to be 14.54 cm. Which of the conclusions summarizes the data? a)   Student A has done the most precise work and student C the most accurate. b)   Student C has done the most precise and accurate work. c)   Student C has done the most precise work and student A the most accurate. d)   Student C has done the most precise work and student B the most accurate. e)   Student B has done the most precise work and student C the most accurate.

Significant figures All digits of a measured quantity are called significant figures

Dimensional analysis (also known as the factor-label method or unit-factor method) Why is this important? Whatever you measure, you have to use units