What is Chemistry?. Chemistry is the study of the structure, function, and properties of matter and the changes it undergoes . What are Chemicals?. Chemicals are substances with a definite composition. Matter and its Properties. Matter is anything that has mass and volume.
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What is Chemistry? Chemistry is the study of the structure, function, and properties of matter and the changes it undergoes.
Solids • Have a shape that does not change • Cannot be squashed • Do not flow
Solids • Low energy • Particles vibrate • Close together • Regular pattern
Liquids • Take the shape of the container • Cannot be squashed • Can flow
Liquids • Medium energy • Move around • Close together • Not a regular pattern
Gases • Fill the container they are in • Have a volume that can change • Can be squashed • Can flow
Gases • High energy • Move fast • Far apart • Irregular arrangement
song Video Shape of container Fills container Fixed Fixed Fixed Changes No No Yes
No shape, fills containers Definite size, takes shape of container Definite High Medium Low Difficult to squash Changes shape, difficult to squash Easy to squash Streamlined shapes move through easily Things move through easily No
Example: 546 µm = .000546 m Example: 0.56 L = 560 ml Example: 1000 g = 1 kg Converting within a specific quantity requires moving the decimal place.
The Metric Number Line We are mostly interested in measurements from the kilo to milli – region of the number line. Use a device to help you remember the order of the prefixes. Kind Hearted Dads Make Dark Chocolate Milk
Temperature is a measure of the average kinetic energy of the particles in a sample of matter. The units that can be used for temperature are Kevin (K) or Celsius (0C). The instrument used to measure temperature is the thermometer.
Kinetic energy is the energy an object has due to its motion. Gas molecules move faster than the molecules in solids and liquids, and therefore, have more kinetic energy. Gas molecules Liquid molecules Solid Molecules
Heat is the energy transferred as a result of a temperature difference. Left undisturbed, energy will flow from objects of high temperature to objects of low temperature until the objects have equal temperature. Unit – Joules (J) or Calories (cal) 1 cal – 4.184 J 1000 cal = 1 kcal also called 1 food Calorie
Accuracy is how close a measurement is to the actual(accepted) value. Example: Your watch is accurate if it is close to the time kept by the National Institute of Standards and Technology (N.I.S.T.)
Significant Figures or Digits The number of reliable digits in a measurement based on accuracy of the measuring instrument. The last digit in the number may be an estimated one.
Rules for Significant Digits Digits other than zero are significant. Example: 947.3 - 4 significant figures 2. Zeros between other significant digits are significant. The oreo effect! 20,047 has 5 significant figures Leading zeros are NEVER significant. Put numbers with leading zeros into scientific notation Ending zeros are significant if the decimal point is expressd. 500.0 4 sig. fig.
Rule 2: All zeros between nonzero (or significant) digits are significant Translation: In between 0s must be measured • Samples • a. 202 mm • b. 1003 cm • c. 0.200105 m • SD’s and precision • a. 3 sd to the mm • b. 4 sd to the cm • c. 6 sd to the mm
Rule 3: Zeros to the right of a nonzero digit but to the left of an understood decimal are NOT significant unless otherwise indicated. Translation: 0s at the end of a whole number are NOT measured unless marked. • a. 200 cm • b. 109,000 m • c. 1,000,000 mm • d. 200 cm • e. 200 cm • a. 1 sd to the m • b. 3 sd to the km • c. 1 sd to the km • d. 3 sd to the cm • e. 2 sd to the dm (a bar over a zero indicates the last measured zero)