Organization of the Periodic Table

Atomic Number
Every element has an atomic number. This is the number of protons in its atom. A proton is a positively-charged particle in an atom. For example, the element copper has 29 protons in its atom. If you read the periodic table left to right and row by row, the atomic numbers will increase in order until you get to number 57. This is because elements 58-71 and 90-103 appear in order in the two rows at the bottom of the periodic table, which are called the lanthanides and actinides. This number also tells you the number of electrons in a stable atom.

Symbols
Each element is assigned a symbol. The symbol usually corresponds to the element's name. Symbols are usually two letters. However, some symbols have one or three letters.

Families
Each vertical column on the periodic table is an element family. All of the elements in each family have similar properties. They usually react the same in chemical reactions, and they may even look the same and be used for the same purposes. Each family is numbered and has a name. Most periodic tables show the number;'some will even give the name.

Periods
Each horizontal row is called a period. There are seven periods on the periodic table. The lanthanides and actinides really fit in with the sixth and seventh periods. They have been written at the bottom of the table for convenience. The periods tell us the number of VALENCE electrons that the atom contains In Period one, the atoms have one valence electron in their outer shell. Valence electrons are the electrons contained in the valence shell (the outermost electron level) of an atom and which are likely to participate in a chemical reaction through bonding with other atoms, molecules or ions. Different atoms have differents number of levels and different numbers of electrons in those levels, but the levels can only hold a certain number of electrons. The first level, closest to the nucleus, can only hold two electrons. The second level can hold 8, the third level 18, fourth level 32, fifth level 32 and the remaining electrons will be found in the sixth level. None of the known elements have filled the sixth level. (2 + 8 + 18 + 32 + 32 = 82 and the highest number of electrons in a known element is 110, leaving only 28 for the sixth level.

Atomic Mass
The atomic mass tell the average mass of the element. The mass comes from the protons and the neutrons found in the nucleus of the atom. It is an average, since different isotopes have different numbers of neutrons. To find the number of neutrons in an atom, subtract the atomic number (the number of protons) from the atomic mass (total of protons and neutrons. )

Metals, Nonmetals, and Metalloids
Some periodic tables show a bold line in the shape of steps on the right side of the periodic table. All the elements to the left of that line are metals. You can probably see that most of the elements are metals. Metals are elements that are good conductors of heat and electric­ity. They have a shiny, metallic luster. Metals can also be pounded into shapes or drawn into wire.
All of the elements to the right of the bold step-shaped line are called nonmetals. Non-metals are poor conductors of heat and electricity. They usually have a dull or earthy luster. When pounded, nonmetals usually shatter or form powders.
The elements that touch the bold step-shaped line are called metalloids. These ele­ments have characteristics of both metals and nonmetals.

Solid, Liquid, or Gas
Some periodic tables even tell us whether an element is a solid, liquid, or gas at room temperature. This is sometimes done by color or by the type of print used. Most elements are solids. There are a few gases. Only mercury and bromine are liquids at room temperature. All elements can be solids, liquids, and gases; it simply depends on the temperature.

Radioactivity
Some elements are radioactive and do not have a stable form. Radioactive means that they naturally give off particles. All the elements with an atomic number of 84 or greater are radioactive. Technetium (43) and promethium (61) also have no stable form. All elements have radioactive forms, and most elements have stable forms. Some periodic tables show whether an element is radioactive or stable.

Natural or Manmade
Most of the elements that we see on the periodic table are natural. This means that they occur somewhere in nature. These are called the natural elements. Synthetic elements are elements that are made by humans in laboratories. Many of the heavier elements are synthetic. It was once thought that neptunium (93) and plutonium (94) were synthetic, but now they have been found in small amounts in nature. All of the elements with an atomic number of 95 or greater are synthetic. Some periodic tables show whether an element is natural or synthetic.

Element Symbols

Every Element Has a Symbol. All the elements have symbols. The symbols are used as akind of shorthand for writing chemical formulas and equations. Many scientists only write thesymbols and never write the true name of the element. The system used for making the sym­bols is as follows.

One-Letter Symbols. Fourteen (14) elements on the periodic table have one-letter sym­bols. The one-letter symbols are always capitalized.
Example: The symbol for carbon is C.

Two-Letter Symbols. Ninety-five (95) elements have two-letter symbols. In these ele­ments the first letter is always capitalized and the second letter is always in the lowercase.
Example: The symbol for neon is Ne.

Three-Letter Symbols. The last three (3) elements in this periodic table have three-lettersymbols. The first letter is always capitalized and the last two are in the lower case.These are all new elements and have not yet been officially named. New elements aregiven Latin names that correspond to their atomic numbers. Some periodic tables todaylist elements up to #118.
Example: The symbol for ununbium is Uub.

Elements

What Are Elements?
Elements are pure substances made of only one kind of atom.
Atoms are tiny structures found in all matter.
Most substances contain many different atoms.
Only the elements contain only one kind of atom.
Salt
Sodium and Chlorine
ELEMENTS
1. One kind of atom
2. Pure
3. Separated in nuclear reactions
Gold
Jewelry
Aluminum
Soda Can
COMPOUNDS
1. Two or more kinds of atoms chemically bonded
2. Pure
3. Separated in chemical reactions
Water
Hydrogen and Oxygen
MIXTURES
1. Two or more elements or compounds physically together
2. Not pure
3. Separated in physical reactions
Italian Dressing
The Periodic Table of the Elements
The periodic table was first constructed in 1869 to organize the elements by their properties. The periodic table in this book shows 112 elements. It organizes them by their families, atomic numbers, and many other properties.


Ancient Times
Some elements were known and used by ancient civilizations. These elements were:
Iron (-2500 BCE) Tin (-2100 BCE) Antimony (-1600 BCE) Lead (-1000 BCE)
Carbon (pre-history) Sulfur (pre-history) Copper (-5000 BCE) Silver (-3000 BCE) Gold (-3000 BCE)

Alchemy to the First Periodic Table (1000-1869)
During this time, 52 elements were discovered. Many of these elements were discovered by alchemists. Alchemists were people who tried to combine science and magic. They tried to change lead into gold. They discovered and used the scientific method. A few elements that were discov­ered during this period were:
Nitrogen (1755) Oxygen (1774) Chlorine (1774) Aluminum (1825)
Arsenic (-1250) Zinc (-1500) Phosphorus (1669) Platinum (-1700) Nickel (1751)

Enter the Periodic Table
The first periodic table was drawn by a Russian scientist named Dimitry Mendeleyev in 1869. Mendeleyev put all 62 known elements on the first periodic table, and even allowed enough space for over 20 elements that had not yet been discovered. Mendeleyev's first periodic table closely resembles the table we use today. He also arranged the elements in the order of their atomic numbers, just as we do today.


Rare and Radioactive Elements (1869-1899)
Many rare and radioactive elements were discovered during this modern period. Rare ele­ments are elements that occur in very small amounts on earth. Radioactive elements are ele­ments that give off small particles. A few elements discovered during this period include:
A.4
Fluorine (1886) Argon (1894) Helium (1895) Krypton (1898)
Neon (1898) Polonium (1898) Radium (1898) Actinium (1899)

Rare, Radioactive, and Synthetic Elements (1900-present)
During this modern period in chemistry, 30 elements have been created or discovered so far. These 20th-century elements are very rare on earth. Some of them are very radioactive. Many of them are not found on earth at all, but were created in a laboratory. These are called syn­thetic elements. Some of these rare, radioactive, and synthetic elements include:
Radon (1900) Francium (1939) Plutonium (1940)
Americium (1944) Dubnium (1970) Ununbium(1996)
The Future

More new elements may be created in the future. Some periodic tables today provide space for elements up to #118. Many scientists are wondering why we should create new elements. Synthetic elements are very radioactive, they decay very quickly, and they cannot be studied or used. Other scientists are creating more elements because they believe that a stable, usable element may be discovered. Some scientists have even predicted that element #114 may be stable. Who knows? Perhaps this stable element will be discovered in your lifetime.

Section 2 Earths Moon

Section 2 Earth’s Moon

A. The Moon’s surface
1. Maria—dark-colored areas that look like oceans formed by lava flows
2. Lunar highlands—higher elevation
3. Craters—depressions formed by meteorites striking the surface
B. The Moon’s interior: crust; mantle; small, dense, iron core
C. Motions of the Moon
1. The Moon always keeps the same side facing Earth.
a. It takes the Moon 27.3 days to orbit Earth.
b. It also takes the Moon 27.3 days to rotate once on its axis.
2. Moon phases—As the Moon orbits around Earth, we see different amounts of its sunlit surface.
a. New moon—The Moon is between Earth and the Sun. The lighted part faces away from Earth.
b. The Moon’s phases wax, or grow in size, as the Moon travels around Earth and we see more of the lighted part.
c. Full moon—Earth is between the Sun and the Moon; the entire lighted part of the Moon faces toward Earth.
d. The Moon’s phases wane, or decrease in size, and we see less of the lighted part.
e. The complete cycle takes 29.5 days.
D. Eclipses—shadows cast by Earth or the Moon onto each other
1. Only occur when the Sun, the Moon, and Earth are perfectly lined up
2. Solar eclipse—The Moon blocks sunlight from reaching a portion of Earth’s surface.
3. Lunar eclipse—Earth blocks sunlight from reaching the Moon; the full moon becomes dark.

Earth in Space

Earth in Space

Section 1 Earth’s Motion and Seasons

A. Earth is a sphere because gravity acts on it.
1. Gravity is a force that attracts all objects toward each other.
2. Gravity depends on how far apart and how large the objects are.
B. Motions of Earth
1. Axis—the imaginary line drawn from the north geographic pole through Earth to the south
geographic pole
2. Rotation—the spinning of Earth on its axis; causes day and night
3. Revolution—the motion of Earth traveling around the Sun
a. Earth’s revolution causes seasons.
b. Earth’s elliptical path around the Sun is called an orbit.
4. Solstices and Equinoxes
a. Because Earth’s axis forms a 23.5 degree angle, the Sun’s position relative to Earth’s equator
constantly changes.
b. Summer and winter solstices—the longest and shortest days of the year; when the Sun
reaches its greatest distance north or south of the equator
c. Equinox—when the Sun is directly over the equator

Measuring in SI

The metric system of measurement was developed in 1795. A modern form of the metric system, called the International System, or SI, was adopted in 1960. SI provides standard measurements that all scientists around the world can understand.
The metric system is convenient because unit sizes vary by multiples of 10. Prefixes are used to name units. Look at the table below for some common metric prefixes and their meanings. Do you see how the prefix kilo- attached to the unit gram is kilogram, or 1,000 g?

Measuring Length
Now look at the metric ruler on your desk. The centimeter lines are the long, numbered lines, and the shorter lines are millimeter lines. When using a metric ruler, line up the 0-cm mark with the end of the object being measured, and read the number of the unit where the object ends.

Liquid Volume
The unit that is used to measure liquids is the liter. A liter has the volume of 1,000 cm?. The prefix milli- means "thousandth (0.001)." A milliliter is one thousandth of 1 L and 1 L has the volume of 1,000 mL. One milliliter of liquid completely fills a cube measuring 1 cm on each side. Therefore, 1 mL equals 1 cm.

Beakers and graduated cylinders are used to measure liquid volume. The surface of liquids is always curved when viewed in a glass cylinder. This curved surface is the meniscus. A meniscus must be looked at along a horizontal line of sight as in the picture below. A graduated cylinder is marked from bottom to top in milliliters. This graduated cylinder contains 79 mL of a liquid.

Graduated cylinders measure liquid volume

Mass
Scientists measure mass in grams. You will use a beam balance similar to the one shown below. The balance has a pan on one side and a set of beams on the other side. Each beam has a rider that slides on the beam.


A triple beam balance is used to determine the mass of an object.

Before you find the mass of an object, slide all the riders back to the zero point. Check the pointer on the right to make sure it swings an equal distance above and below the zero point. If the swing is unequal, find and turn the adjusting screw until you have an equal swing.

Place an object on the pan. Slide the largest rider along its beam until the pointer drops below zero. Then move it back one notch. Repeat the process on each beam until the pointer swings an equal distance above and below the zero point. Sum the masses on each beam to find the mass of the object. Move all riders back to zero when finished.
You should never place a hot object on the pan or pour chemicals directly onto the pan. Instead, find the mass of a clean container. Remove the container from the pan, then place the chemicals in the container. Find the mass of the container with the chemicals in it. To find the mass of the chemicals, subtract the mass of the empty container from the mass of the filled container.

Metric Conversions

Some things to Remember when converting any type of measures:
To convert from a larger to smaller metric unit you always multiply To convert from a smaller to larger unit you always divide
The latin prefixes used in the metric system literally mean the number they represent. Example: 1 kilogram = 1000 grams A kilo is 1000 of something just like a dozen is 12 of something.
This is the metric conversion stair chart. You basically take a place value chart turn it sideways and expand it so it looks like stairs. The Latin prefixes literally mean the number indicated. Meter, liter or gram can be used interchangeably.
You use this chart to convert metric measurements like this:
If you are measuring length use meter.
If you are measuring dry weight use grams.
If you are measuring liquid capacity use liter
For every step upward on the chart you are dividing by 10 or moving the decimal one place to the left.. Example: To convert 1000 milligrams to grams you are moving upward on the stairs: Pretend you are standing on the milli-gram stair tread and to get to the 1-gram stair tread you move up 3 steps dividing by 10 each time. 1000/10 = 100 100/10 = 10 10/10 = 1 or
1000/1000 = 1 or use the shortcut and just move the decimal place one place to the left with each step
1000 milligrams = 1 gram.
When you move down the stairs you are multiplying by 10 for each step. SO you are adding a zero to your original number and moving the decimal one place to the right with each step. Example: To convert 2 kilometers to meters you move 3 steps down on the chart so you add 3 zeros to the 2. 2 kilometers = 2000 meters