THE PERIODIC TABLE (Chapter 6) https://www.youtube.com/watch?v=VgVQKCcfwnU https://www.youtube.com/watch?v=7nGz7xgGJzc

Organizing the Elements Few elements, including copper, silver, and gold, have been known for thousands of years There were only 13 elements identified by the year 1700 Chemists began to use scientific methods to search for elements, the rate of discovery increased In one decade (1765–1775), chemists discovered five new elements

J. W. Dobereiner, published a classification system Early chemists used the properties of elements to sort them into groups J. W. Dobereiner, published a classification system The known elements were grouped into triads A triad is a set of three elements with similar properties

Mendeleev arranged elements with… Mendeleev arranged elements with…. similar properties in the same row (organized by atomic mass)

Mendeleev placed tellurium before iodine in his periodic table The problem wasn’t with the atomic masses but with using atomic mass to organize the periodic table Mendeleev placed tellurium before iodine in his periodic table https://www.youtube.com/watch?v=nsbXp64YPRQ

Today’s Periodic Table In the modern periodic table, elements are arranged in order of increasing atomic number (number of protons in the nucleus)

Properties of the elements within a period change as you move across a period from left to right. Pattern of properties within a period repeats as you move from one period to the next Elements that have similar chemical and physical properties end up in the same column in the periodic table https://www.brainpop.com/science/matterandchemistry/periodictableofelements/

Metals, Nonmetals, Metalloids https://www.brainpop.com/science/matterandchemistry/metals/

Metals Good conductors of heat & electrical current Luster (shiny) Solid at room temperature except Mercury (Hg) Malleable & ductile Nonmetals Poor conductors of heat & electrical current Most are gases at room temperature (main components of air—nitrogen and oxygen) Few are solids (sulfur and phosphorus) & Bromine (Br) is a liquid Brittle Metalloids Properties similar to those of metals & nonmetals (depending on conditions) Silicon is used in computer chips

What information can be learned about the elements on the periodic table? Drivers license tell us information…..Name, eye color, height, weight, address, date of birth (unique to each individual)

What Information can we get about an element?

SOLIDS, LIQUIDS, GASES Solids chemical symbol is in black Gases chemical symbol is in red Liquids chemical symbol is in blue **Could be three different colors on a different periodic table (these colors are in reference to the ones in your textbook)

Groups/Families of the Periodic Table The elements in Group 1 are called alkali metals The elements in Group 2 are called alkaline earth metals

The nonmetals of Group 7 are called halogens The nonmetals of Group 8 are called Noble Gases

Transition Elements Transition metals Displayed in the main body of the periodic table Copper, silver, gold, and iron are transition metals Characterized by the presence of electrons in d orbitals Inner transition metals Appear below the main body of the periodic table Characterized by the presence of electrons in f orbitals(4f & 5f) https://www.youtube.com/watch?v=xqoQfN9DgNs

Representative Elements Elements in Groups 1-2 and 3-7 (s and p blocks) are often referred to as representative elements They display a wide range of physical and chemical properties.

Valence Electrons The number of outer or “valence” electrons in an atom affects the way an atom bonds All atoms want to acquire an octet (8 electrons in the outer shell)… this is why atoms bond together! Atoms gain or lose electrons (forming ions) to obtain the octet

There are different ways to determine the number of outer shell VALENCE electrons in a given element Electron configuration Bohr Diagrams Group Number (Representative elements)

Electron Configuration

Bohr Diagrams

DETERMINING VALENCE ELECTRONS

For any representative element its group number equals the number of valance electrons (electrons in the highest occupied energy level)

IONS An ion is an atom or group of atoms that has a positive or negative charge Atoms become ions when electrons are lost or gained Atoms can become cations or anions

Cation (Positively charged ion) More positively charged protons than negatively charged electrons, the ion has a net positive charge The charge for a cation is written as a number (number of electrons lost) followed by a plus sign Metals tend to form cations

Anion (Negatively Charged ion) More negatively charged electrons than positively charged protons, the ion has a net negative charge The charge for an anion is written as a number (number of electrons gained) followed by a minus sign Nonmetals tend to form anions

PERIODIC TRENDS Chapter 6.3

Atomic Size The size is expressed as an atomic radius The atomic radius is the distance from the nucleus to the outermost energy level

In general, atomic size increases from top to bottom within a group, and decreases from left to right across a period

Rubidium, Gallium, Potassium Practice Question.... 1. Which of the following has the smallest atomic radius? Rb, Cs, O 2. Order the following atoms in increasing atomic radius (smallest to largest) Rubidium, Gallium, Potassium

Ionization Energy Ionization energy is the energy required to remove an electron from an atom Ionization energy tends to decrease from top to bottom within a group and increase from left to right across a period

Practice Question... 1. Which of the following elements has the lowest ionization energy Sodium, Lithium, Potassium, Fluorine 2. List the following elements in increasing ionization energy Chlorine, Lithium, Oxygen, Beryllium