5. Periodic Table

90

Scientists have identified _ naturally occurring elements

28

Scientists created about _ elements.

oxygen

The most abundant element in the earth’s crust

Periodic Table

Organizes the elements in a particular way. A great deal of information about an element can be gathered from its position

118

how many elements are there in a periodic table?

Atomic Number

Refers to how many protons an atom of that element has.

Atomic Mass

Refers to the “weight” of the atom.

Atomic Mass

It is derived at by adding the number of protons with the number of neutrons

Isotopes

different forms of the same chemical element that have the same number of protons but a different number of neutrons

Atomic Mass Unit (AMU)

The unit of measurement for an atom.

One AMU

equal to the mass of one proton

6x10^23

how many amus are there in one gram?

Symbols

Consist of a single capital letter, or a capital letter and one or two lower case letters

Valence Electrons

The electrons in the outer energy level of an atom.

Valence Electrons

These are the electrons that are transferred or shared when atoms bond together

Metals

Good conductors of heat and electricity. Shiny, ductile, and malleable.

corrosion

A chemical property of metal is its reaction with water which results in _

Non-Metals

Poor conductors of heat and electricity. Not ductile or malleable.

Solid non-metals

brittle and break easily. They are dull.

gases

Many non-metals are _

Metalloids

Have properties of both metals and non-metals.

Metalloids

Solids that can be shiny or dull. Ductile and malleable.

Metalloids

Conduct heat and electricity better than non-metals but not as well as metals.

Families

Columns of elements called groups or _.

family

They have similar but not identical properties. All elements in a _ have the same number of valence electrons

Periods

Horizontal rows of elements.

active solid

The first element in a period is always an extremely _.

inactive gas

The last element in a period is always an _.

Hydrogen

Sits atop Family AI, but it is not a member of that family. In a class of its own.

Hydrogen

A gas at room temperature. Has one proton and one electron in its one and only energy level.

Hydrogen

Only needs 2 electrons to fill up its valence shell

Alkali Metals

Found in the first column of the periodic table. Atoms have a single electron in their outermost level, in other words, 1 valence electron.

Alkali Metals

Shiny, have the consistency of clay, and easily cut with a knife

Alkali Metals

They are the most reactive metals. They react violently with water.

Alkali metals

never found as free elements in nature. They are always bonded with another element.

Reactivity

Describes elements that bond easily with other elements to make compounds. Caused by an incomplete valence electron level.

octet rule

All atoms (except hydrogen) want to have 8 electrons in their very outermost energy.

Alkaline Earth Metals

Never found uncombined in nature.

Alkaline Earth Metals

Have two valence electrons.

Transition Metals

Found in the B families. Good conductors of heat and electricity.

Transition Metals

Their compounds are usually brightly colored and are often used to color paints.

Transition elements

have 1 or 2 valence electrons, which they lose when they form bonds with other atoms. Some can lose electrons in their next-to-outermost level.

Transition Elements

Have properties similar to one another and to other metals, but their properties do not fit in with those of any other family.

oxides

Many transition metals combine chemically with oxygen to form _

aluminum

the most abundant metal in the earth’s crust.

Boron Family

Atoms in this family have 3 valence electrons.

Carbon Family

Atoms have 4 valence electrons.

carbon

The element that is called the “basis of life.”

Nitrogen Family

Named after the element that makes up 78% of our atmosphere.

Nitrogen Family

Atoms have 5 valence electrons and tend to share electrons when they bond

Oxygen Family

Atoms have 6 valence electrons. Most elements share electrons when forming compounds.

Halogen Family

Have 7 valence electrons, making them the most active non-metals. Never found free in nature.

Halogen Family

atoms need to gain 1 electron to fill their outermost energy level. React with alkali metals to form salts

Noble Gases

Colorless gases that are extremely un-reactive.

Noble Gases

Inactive because their outermost energy level is full.

inert

Noble gases are called _ because they do not readily combine with other elements

30

How many rare earth elements are there?

lanthanide and actinide

the rare earth elements are composed of these 2 series

trans-uranium

One element of the lanthanide series and most of the actinide series are called _, meaning synthetic or man-made

Dmitri Ivanovitch Mendeleev

In 1869, he created the first accepted version of the periodic table. Grouped elements according to their atomic mass. Found that the families had similar chemical properties and left blank spaces for predicted elements

Molecules

All matter is composed of atoms and groups of atoms bonded together, called _.

Pure Substances

Substances made from one type of atom only.

Compounds

Substances made from more than one type of atom bonded together.

Mixtures

Compounds that are combined physically, but not chemically.

Compounds

Have different properties than the elements that make them up.

a.) sodium b.) chlorine

Table salt has different properties than a.)_ , an explosive metal, and b.) _, a poisonous gas.