A Little Periodic Table History…

History of the Periodic Table Dmitri Mendeleev, a Russian scientist born in Siberia in 1834, is known as the father of the periodic table of the elements The periodic table is designed to help you predict chemical and physical properties of elements

Method Behind the Madness Mendeleev set out to find a pattern in the elements He wrote facts on paper cards for each element Melting Point Density Colors Atomic Masses

Method Behind the Madness (cont) After laying all of his cards out he noticed that by arranging them according to their properties they were arranged in order of increasing atomic mass Mendeleev was even able to use the patterns in his table to predict the properties of undiscovered elements The first periodic table was published in 1869 The Genious of Mendeleev's Periodic Table - TedEd Mendeleev Song

Today, elements are arranged in order of increasing atomic number on the periodic table Big Science Idea

Element Location Elements are located in three main categories on the periodic table based on their physical properties Metals Nonmetals Metalloids

Physical Properties Physical Property - a property of matter that can be observed or measured WITHOUT CHANGING the substance

Examples of Physical Properties Color/Texture Mass – How much matter is in an object Malleable – Can be pounded/rolled into a shape Ductile – Can be stretched into a long wire Density – How tightly mass is packed into an object

Metals, Nonmetals, & Metalloids

Metals Most elements are metals. The 88 elements to the left of the stair-step line are metals or metal-like elements. Physical Properties of Metals: high luster (shininess) good conductors of heat and electricity high density (heavy for their size) high melting point ductile malleable

Metals

Non-Metals Non-metals are found to the right of the stair-step line. Their characteristics are opposite those of metals. Physical Properties of Nonmetals: no luster (dull appearance) poor conductor of heat and electricity brittle (breaks easily) not ductile not malleable low density low melting point

Non-Metals

Metalloids Elements on both sides of the zigzag line have properties of both metals and nonmetals. These elements are called metalloids. Physical Properties of Metalloids: solids can be shiny or dull ductile malleable conduct heat and electricity, but not as well as metals Antimony (Sb)

Metalloids

Scientists organize elements according to their physical and chemical properties Big Science Idea

How to Read the Periodic Table The Periodic table is designed to help you predict what an element's physical and chemical properties are You can also predict what elements will bond with each other

Elements are arranged: Vertically into Groups (also called Families) Periodic Table Bitesize (only show part 1) Horizontally Into Periods

Periodic Table Arrangement Groups or Families Vertical columns on the periodic table Periods Horizontal rows of the periodic table

Why?

If you looked at one atom of every element in a group you would see…

Each atom has the same number of valence electrons (the electrons in its outermost shell). Think back to the Bohr Model An example…

The group 2 atoms all have 2 electrons in their outer shells Be (Beryllium) Atom Mg (Magnesium) Atom

Valence Electrons Effect the way an atom bonds, which determines many of the chemical properties of the element Atoms can have anywhere between 1 and 8 valence electrons This is why elements within a group usually have similar chemical properties

Chemical Properties A chemical property is a characteristic that is observed when a substance changes into a different substance

Examples of Chemical Properties Combustible – capable of igniting at higher temps Corrosion Reactivity Flammable – capable of igniting Oxidation – rusting or tarnishing

Reactivity decreases from left to right Metals – Reactivity Reactivity decreases from left to right Metal Reactivity

Nonmetals – Reactivity Reactivity increases from left to right Not Reactive X

If you looked at an atom from each element in a period you would see…

Each atom has the same number of electron holding shells. An example…

The period 4 atoms each have 4 electron containing shells 4th Shell K (Potassium) Atom Kr (Krypton) Atom Fe (Iron) Atom

Each group has distinct properties The periodic Table is divided into several groups based on the properties of different atoms For example…

The periodic table tells us several things…

Periodic Table Information on the periodic table: Atomic number Atomic symbol Mass number (Atomic Mass) Element name Group and period numbers

O Think Inside the Box Oxygen 8 16 Atomic Number: Number of protons (also the number of electrons) in an atom of an element. O Oxygen 16 8 Element’s Symbol: An abbreviation for the element. Element’s Name Atomic Mass: Number of protons + neutrons.

Chemical Symbols Shorthand way of representing the elements Usually one or two letters Usually taken from the name of the element Carbon-C, Calcium-Ca, Hydrogen-H, Iodine-I, Oxygen-O, Chlorine-Cl

Chemical Symbols Some symbols come from their Latin name: Gold-Au--aurum Silver-Ag--argentum Iron-Fe--Ferrum Mercury-Hg--hydrogyrum

How do we know the number of subatomic particles in an atom? Atomic number: this number indicates the number of protons in an atom of a particular element Ex: Hydrogen’s atomic number is 1 So hydrogen has 1 proton Ex: Carbon’s atomic number is 6 So carbon has 6 protons **The number of protons is a unique property that identifies an element. Ex. 2 protons = He, 29 protons = Cu

Atomic Mass Atomic Mass Unit (amu) is used to measure the particles in atoms Protons & Neutrons are about 1 amu Electrons are MUCH smaller It takes about 2,000 electrons to equal 1 amu Atomic Mass = Protons + Neutrons

Li 6.941 3 Mass # Atomic # Symbol Pick an element off the Periodic Table and draw and label it just like this one!

Group and Period Numbers Group Numbers

APEMAN

How Can I Find Out the Number of Protons and Electrons? Atomic No. = # of protons Since protons & electrons are EQUAL...the atomic no. also tells you the # of electrons *Atomic # = # of Protons = # of electrons*

Atomic # = # of Protons = # of electrons APE Let’s take a look: A = Atomic number P = Number of protons E = Number of electrons These are all the same number!! So Atomic # = # of Protons = # of electrons

Neutrons = Mass Number – Atomic Number Then How Can I Find Out the Number of Neutrons? Mass Number = number of protons + number of neutrons So Neutrons = Mass Number – Atomic Number

MAN Now let’s look at MAN: M= Atomic Mass - A= Atomic Number N= # of Neutrons Simple math! Mass minus atomic number gives you the number of neutrons!!!

APEMAN Let’s work a couple together Let’s try Nitrogen!

Nitrogen Boron 5 7 A= P= E= M= -A= N= A= P= E= M= -A= N= 5 7 5 7 11 14 5 7 6 7

Now that we know how to figure out protons, electrons, and neutrons… Let’s try to create a Bohr Model

Lithium Li Lithium Electrons = Atomic Structure Electrons = 3 (2 in the 1st shell, 1 in the 2nd shell) - + 3 Li Lithium 7 Protons = 3 Neutrons = 4 (7-3 = 4)

Protons determine an element’s identity and valence electrons determine its chemical properties Big Science Idea

SUMMARY The Atomic Number of an atom = number of protons in the nucleus. The Atomic Mass of an atom = number of Protons + Neutrons in the nucleus. The number of Protons = Number of Electrons. Electrons orbit the nucleus in shells. Each shell can only carry a set number of electrons.