Chemistry Unit 1 Notes

Chemistry Unit 1 Notes

Chemistry-the study of chemicals including changes chemicals undergo.

A chemicalis any substance that has a definite composition-made of the same stuff

A chemical reaction has two parts:

Elements involved –Reactant

Substances formed by the chemical reaction–Product

Example: Na(s) + Cl (g)NaCl (s)

FOUR STATES OF MATTER

Solid-The atoms or molecules are strongly attracted to one another and tightly packed. Exs.- table, book, chair

Liquid-The atoms or molecules are attracted to each other, but not as strongly as those of a solid are. They are free to move over and around each other. Ex.- water

Gas-The atoms or molecules are not strongly attracted to each other. They move freely and independently of one another. Exs.- O, H, He

Plasma-The most common form. They are composed of ions and electrons moving freely. Exs.-Stars, lightning bolts

Physical change-A change in which the same substance is present before and after the change. Note that its state of matter can change though. Exs.: cutting, melting, boiling
Chemical change-Is a rearrangement of atoms and/or molecules to produce one or more new substances with new properties. Exs.: burning, fermenting, oxidation

Matter-Is anything that has volume and mass

Volume (liquid measure in L) and for soliduse the following formulas:
Density formula D=m/v so for v= m/D
Volume= LxWxH= units3
Area formula: L x W= units2
Mass-the quantity of matter in an object that depends on the number of atoms and kinds of atoms the object is made of.
Solid mass is measured on a scale or balance beam (SI Unit is kg)
Formula to calculate mass: m= D x v
Weight-the force produced by gravity acting on the mass

A theory is an explanation of a natural phenomenon that is supported by a large body of scientific evidence obtained from many different investigations and observations.

Results from continual verification and “fine-tuning” of a hypothesis.

A law is recognized to be a fact of nature

Law of Gravity
Law of conservation of mass-the products of a chemical reaction have the same mass as the reactants have.

Quantitative data is measured.

Time, temperature, length, mass, volume

Qualitative data is a verbal description.

Behavior, color, etc.

Unit of Measurement

International System of Units (SI Units) is based on a decimal system using the #10 as a base.

Second (s) is the SI Unit for time
Kelvin (K) is the SI Unit for temperature
Formula: K=oC+273.16
Formula for oC: K-273.16= oC

Length- The distance between point A and point B
Meter is the SI Unit for length
Kilogram (kg)is the SI Unit for mass

Conversion factor

English to Metric/ English to English Metric to Metric: Meters (m), Liters (L), and Grams (g)

1 inch = 2.54 cm / 1,000,000,000,000 pm (picometers) =1 m (meter)
1,000,000,000 nm (nanometers)= 1 m
12 inches =1 ft / 1,000,000 µm(micrometers) = 1 m
1 minute= 60 seconds / 1,000 mm (millimeters) = 1 m
1 hour = 60 minutes / 100 cm (centimeters) = 1 m
1 Day = 24 hours / 10 dm (decimeters)=1 m
0.2390 cal (calories) = 1 J (Joule) / 1 dam (decameter) = 10 m
1 Calorie (C) =1000 cal or 1 kcal / 1 hm (hectometer) = 100 m
101305 Pa = 1 atm (atmosphere) / 1 km (kilometer) = 1000 m

Percent Error= (your value-literature value)/literature value x 100 (Units are in %)

Other Energy Conversion of calories to joules

0.2390 calories (cal) = 1 Joule (J)

1 cal=4.184 J

1 Cal = 1kcal

1 kJ=1000 J

Significant Figures/Digits Rules (see pp. 57-58 of textbook)

Nonzero digits are always significant.
Example: 1234 4 SD
Zeros between nonzero numbers are significant
Example: 1.0234 5 SD
Zeros in front of nonzero digits are not significant
Example: 0.1234 4 SD
Zeros both at the end of a number and to the right of a decimal point are significant
Example: 0.12340 5 SD
Example: 10.00 4 SD
Zeros both at the end of a number but to the left of a decimal point may not be significant.
If a zero has not been measured or estimated, it is not significant.
1000 1 SD
1000. 4 SD
A decimal point placed after zeros indicates that the zeros are significant.
1000.00 6 SD

Calculations Using Significant Figures

In multiplication and division problems, the answer cannot have more significant digits than there are in the measurement –Go by the lowest number of significant digits to determine final answer
16 x 9 the lowest SD is 1 so the answer is 100 instead of 144
In addition and subtraction of numbers, determine the number of significant digits for each component after the right of the decimal point.
166.36-24 166.36

-24

142 36 Final answer is 142

Scientific Notation

The first number of scientific notation must be 1 to 9.
Basically the number of spaces you move from the decimal right or left determines the exponent.
If you move to the left the exponent will be positive
Example: 1000.6 would equal 1.0006 x 103
If you move to the right the exponent will be negative
Example: 0.00234 would equal 2.34 x 10-3

Physical property-Characteristics of an element or a compound that affect weight, color, density, etc., but do not change the substance.

TWO TYPES OF PHYSICAL PROPERTIES

Extensive property-Depends on the amount of matter present. Exs.: mass, length, volume
Intensive property-Independent of the amount of matter present. Exs.: Most important factor is color, density, malleability, ductility, and conductivity, crystalline shape, melting point, boiling point, refractive index.

Chemical property-Characteristics of an element or a compound that determine how it will chemically react with other elements or compounds.

How Is Matter Classified?

Atoms: The building blocks of matter and the smallest particle of an element that exhibits characteristics of that element.

Elements: A pure substance that cannot be broken down into simpler substances except by nuclear means.

Elements are made of all the same atoms.
92 elements are natural occurring and the others are made in a lab (synthetic)
Most two abundant in the universe is Hydrogen 93.5% and Helium 6.3 %
Most two abundant on Earth are Oxygen 46.6 % and Silicon 27.7 %
Most elements are identified by a one or two letter abbreviation called symbol (some have three letters).
The first letter is capitalized and the second (or third) are lower cased.
Some symbols are only one letter
Only 25 are essential to living organisms.
C, H, N, and O-together make up 96% of the mass in the human body
Trace elements are present in living things in very small quantities.
Ex. Cu and Fe

Compounds: is a pure substance that is composed of atoms of two or more different elements that are chemically combined. Each of the elements in the compound lose their chemical characteristics when chemically bond.

A molecule is a compound usually containing two or more atoms combined in a definite ratio.
Example: water

Mixture: (not a pure substance) Combination of two or more components that retain their identities. Can be broken down by physical means.

Two Types

Heterogeneous mixture: Not evenly distributed and often different parts of the mixture have different properties. Ex. Soil
Homogeneous mixture: The substances are uniformly distributed, so all parts have the same properties. Ex. Steel, air, brewed coffee, and Kool-Aid

Solution: 2 parts solute (what is being dissolved) and solvent(What is doing the dissolving) and are always a homogeneous mixture

Most are liquid like salt water and magma, but some are solids like bronze (from Tin and Copper) and brass (from Copper and Zinc) and gases like air (mainly Nitrogen and Oxygen)

Accuracy-Refers to how close the measurement is to the actual value

Precision-Refers to how close a set of measurements is together whether or not the measurements are correct