The Periodic Table The Use of Tables To

The Periodic Table

The Use of Tables To organize data (information) See relationships, patterns, and similarities.

The Periodic Table Lists all the elements in an organized form. Organized by the similar characteristics of the elements. Elements are listed in order of increasing atomic number.

What is an Element? An element is the simplest form of a substance that retains the properties and characteristics of that substance. E. g. : Carbon, C; Hydrogen, H, Nitrogen, N; Oxygen, O.

Chemical Nomenclature In the scientific community, elements are listed and referred to by using symbols. – First letter of name: • Hydrogen = H – First and second letter of name: • Helium = He – First and third letter of name • Chlorine = Cl – Exceptions = Latin names: • Gold = Au (for Auric), Iron = Fe (for Ferric)

The First Table • Dmitri Mendeleev formed the first table organizing the elements by their atomic mass. Also noticed other similarities among elements: • Density • Reactivity • Maleability

Periodic Patterns Mendeleev noticed that these characteristics repeated in a pattern. Repeating patterns are called periodic so he named his table the Periodic Table of the Elements.

Organization of the modern Periodic Table The elements are organized by increasing atomic number and similar characteristics. Elements are similar to other elements found in the same row or column.

• http: //www. ptable. com/

Periods aka Rows The properties of elements in the same period, (row across), gradually change as you move from left to right. Left metals Right non-metals

Groups aka Families • Groups, or “families”, are columns that go up and down in the table. • Elements in the same group, or family, have the same number of electrons in their outer shell. – Elements in the same group will combine with other elements in the same way

Groups with Family Names • Some groups of the periodic table have “family names” that indicate their similar characteristics. – Alkali Metals – Alkaline Earth Metals – Coinage Metals – Halogens – Inert “Noble” Gases

Alkali Metal Family The alkali metals, metals (far left, column 1), are very reactive elements because they have only one electron in their outer energy level. – Easy to loose one electron, therefore very reactive. Alkali metals will immediately react with air, water, and other substances in the environment. Characteristics: soft (cut w/a knife, have luster, and conduct heat and electricity.

Alkaline Earth Metal Family Alkaline earth metals, (column 2), are reactive, (but not as reactive as alkali metals), because they have 2 electrons in their outer energy level. – Fairly easy to loose 2 electrons so fairly reactive. Characteristics: soft (but harder than alkali metals), have luster, conduct heat and electricity.

Coinage Metal Family Contain the metals used to make coins. These metals have various numbers of valence electrons which allows the metals to combine with other metals to form coins. – Copper, Cu; Silver, Ag; Gold, Au

Halogen Family Halogens, (group 17, 2 nd from right), are very reactive gases that contain 7 electrons in the outer energy level. – Easy to gain one electron so very reactive.

Inert, “Noble”, Gases Family • The inert gases (group 18, far right) have full outer energy levels (8 electrons) so they are non-reactive, or “inert”.

What is Reactivity? Reactivity is how easily an element will combine with other elements. – High reactivity = easier to combine Elements combine with other elements by gaining, loosing or sharing electrons.

Reactivity of Metals will lose electrons when they combine with other elements. The farther away electrons are from the nucleus the easier they break away so the bigger metals have higher reactivity.

Reactivity of Non-Metals Non-metals will gain electrons when combining with other elements. The closer electrons are to the nucleus the stronger the force of attraction so the smaller the non-metal the higher the reactivity.

Energy Levels of Elements Energy levels indicate the distance from the nucleus where the electrons are found. – Different energy levels can contain different amounts of electrons. • • K (the first level) can contain 2 electrons L (the 2 nd level) can contain 8 electrons M (the 3 rd level) can contain 18 electrons N (the 4 th level) can contain 32 electrons

Energy of Electrons The closer an electron is to the nucleus, the more energy it takes to separate it from the nucleus. The farther away an electron is from the nucleus, the more energy the electron has.

What are Valence Electrons? Valence electrons are the electrons that are found in an element’s outer-most energy level. Valence electrons are those involved in chemical bonding of elements.

Dot Diagrams A dot diagram is a simple way to show valence electrons and how an element will combine. Dot diagrams only show the element and the valence electrons (those electrons that are available for bonding)

Examples of Dot Diagrams

Why Do Elements Combine? • Elements will combine with other elements to become more stable. • Combining allows elements to fill their outer energy levels.

What is an Ion? • An ion is a charged atom. – An atom that has gained or lost electrons is no longer neutral and now has either a positive “+” or negative “-” electrical charge.

What is an Isotope? • An isotope is an atom of an element that has the same number of protons, atomic number, as another atom but a different number of neutrons.

Elements, Mixtures, and Compounds • Element = the simplest form of a substance that retains the properties of that substance. • Mixture = when 2 or more elements are combined in a manner that the properties of each element do not change. In a mixture the original elements can be separated by physical means. • Compound = a substance formed by the combination of elements in fixed proportions and involving a chemical reaction. In a compound the original elements can not be separated by physical means.

Example of How Elements of the Same Group Will Combine in the Same Way

What is a Chemical Formula? • Chemical formulas, or molecular formulas, are a shorthand representation of the elements of a substance. • Chemical formulas tell the exact makeup of a substance. • Ex. H 2 O = 2 atoms of Hydrogen and 1 atom of Oxygen. • C 6 H 12 O 6 = 6 Carbon, 12 Hydrogen, and 6 Oxygen atoms