Do Now Define an element. What relationship exists between atomic number, protons and electrons?

The Periodic Table

Mendeleev’s Periodic Table Dmitri Mendeleev

History of the Periodic Table By 1860 more than 60 elements had been discovered. Chemists learned about the new elements by reacting them with other elements to form new compounds. In 1865, John Newlands, an English chemist, arranged the known elements according to their properties in order of increasing atomic mass. The properties of elements seemed to repeat every eight elements. This pattern is known as the law of octaves.

History of the Periodic Table In 1869, Dmitri Mendeleev, a Russian chemist, used Newland’s observations and other observations to produce the first PERIODIC Table.PERIODIC He placed each element on a card with the element’s atomic mass, chemical and physical properties. He arranged the elements in many different ways according to various properties and looked for trends. When he arranged the elements according to increasing atomic mass, he noticed that certain similarities occurred at regular intervals. This was considered a “periodic pattern”. He arranged all the elements in a table according to increasing atomic mass, starting a new row every time the pattern repeated, and the elements with similar properties fell in the same vertical columns (with a few exceptions). He had some blank spaces in his table where he thought new elements would be discovered. These blank spaces were used to predict the existence and discovery of new elements.

History of the Periodic Table By 1886 three new elements were discovered that followed Mendeleev’s predication. Most chemists were persuaded to accept his table, labeling Mendeleev the founder of the periodic law.

History of the Periodic Table In order to keep the pattern of properties, Mendeleev had to switch some elements out of order based on atomic mass. In 1911, Henry Mosely, an English chemist, was examining the spectra of 38 different metals. He noticed that the wavelengths of spectra lines correlated to atomic numbers, not atomic mass. Moseley discovered a new pattern and organized the elements according to their increasing nuclear charge, or atomic number, i.e. increasing number of protons. When the elements were arranged by increasing atomic number, the discrepancies in Mendeleev’s table disappeared.

Modern Russian Table

Chinese Periodic Table

Stowe Periodic Table

A Spiral Periodic Table

Triangular Periodic Table

“Mayan” Periodic Table

Meet the Elements Music Video bM bM xE xE

Do Now What do you think of when you hear the word metal? What is a nonmetal? Do you know of any examples of each?

The Periodic Table consists of: METALS NONMETALS METALLOIDS

Properties of Metals Metals are good conductors of heat and electricity Metals are malleable (can be hammered or rolled into sheets) Metals are ductile (can be made into wire) Metals have high tensile strength Metals have luster

Examples of Metals Potassium, K reacts with water and must be stored in mineral oil Copper, Cu, is a relatively soft metal, and a very good electrical conductor.

Examples of Metals Zinc, Zn, is more stable than potassium Mercury, Hg, is the only metal that exists as a liquid at room temperature

Mixing metals Alloy = mixture of a metal with another element, usually another metal Alloys have properties different from the individual elements, usually eliminating some disadvantages. – Alloys are usually harder and more resistant to corrosion Ex: brass = copper + zinc Ex: sterling sliver = copper + silver Ex: steel = iron + carbon + manganese + nickel Ex: Stainless steel = iron + chromium

Properties of Nonmetals Carbon, the graphite in “pencil lead” is a great example of a nonmetallic element. Nonmetals are poor conductors of heat and electricity Nonmetals tend to be brittle Many nonmetals are gases at room temperature

Examples of Nonmetals Sulfur, S, was once known as “brimstone” Microspheres of phosphorus, P, a reactive nonmetal

Examples of Nonmetals Graphite is not the only pure form of carbon, C. Diamond is also carbon; the color comes from impurities caught within the crystal structure Bromine is a nonmetal that exists as a liquid at room temperature.

Properties of Metalloids Metalloids straddle the border between metals and nonmetals on the periodic table. They have properties of both metals and nonmetals. Metalloids are more brittle than metals, less brittle than most nonmetallic solids Metalloids are semiconductors of electricity Some metalloids possess metallic luster

Silicon, Si – A Metalloid Silicon has metallic luster Silicon is brittle like a nonmetal Silicon is a semiconductor of electricity Other metalloids include: Boron, B Germanium, Ge Arsenic, As Antimony, Sb Tellurium, Te

Elements classified as metals and nonmetals

Do Now Take out your Reference Table and open to the Periodic Table of Elements Do you notice any patterns as you look at the properties of elements? – Hints: scan left to right, and scan from the top down

The Periodic Table PERIODIC LAW – The physical and chemical properties of the elements are periodic functions of their atomic numbers (elements with similar properties appear at regular intervals). THE MODERN PERIODIC TABLE – An arrangement of the elements in order of increasing atomic number so that the elements with similar properties fall in the same column or group.

Periodic Table with Group Names PERIODS= Horizontal rows GROUPS= vertical columns

VALENCE ELECTRONS Elements within the same group have the same number of valence electrons.

VALENCE ELECTRONS Most loosely bound electron is called the VALENCE ELECTRON! Valence electrons participate in chemical reactions, so elements with similar valence electrons react in similar ways. Noble gases are stable with ___ valence electrons. All elements with the exception of Hydrogen and Helium want 8 valence electrons to be stable. Hydrogen and Helium want __ valence electrons to be stable.

GROUP 1 Alkali Metals Properties: – Metal – Easily lose valence electron – 1 valence electron – Chemically reactive – do not occur as free elements in nature – Soft, silvery – Good conductor of electricity – React violently with water – React with halogens to form salts

EXCEPTION: Hydrogen is in group 1, but has different properties than the alkali metals

Hydrogen Most common element in the universe. It consists of one proton and one electron. It can react with many other elements: – With oxygen to make water – With carbon to make organic compounds – With nitrogen to make ammonia

GROUP 2 Alkaline Earth Metals Properties: – They are metals, but have less metallic characteristics than Alkali Metals – 2 valence electrons – Chemically reactive – do not occur as free elements in nature – Harder, denser, stronger, higher boiling points, and slightly less reactive than alkali metals

GROUP 17 Halogens (“Salt makers”) Properties: – Most reactive nonmetals. – 7 valence electrons – need 1 electron to become stable – They vigorously react with metals to form salts. F 2 - most reactive element Cl 2 Br 2 I 2

GROUP 18 NOBLE GASES (or INERT GASES) Properties: – Full set of valence electrons: most elements have 8 valence electrons, except Helium with 2 valence electrons, but it is still associated with this group because its properties match these elements. – Extremely stable and occur as monoatomic gases in nature – Although they do not readily combine with other elements, but compounds of Krypton and Xenon have been prepared.

Monoatomic Atoms All of the ____________ gases are monatomic. Monatomic means _____________________.

Transition Metals (d-Block) They have “typical metallic properties” Luster, ductile, malleable, good conductors of heat and electricity Less reactive than Group 1 and 2 Many are unreactive (for example, palladium, platinum and gold are found as pure elements in nature) As ions, the transition elements form colorful solutions. These elements begin in Period 4 and include Groups 3-12.

Lanthanides and Actinides (f-Block) Lanthanide Series- shiny metals similar in reactivity to Alkaline Earth Metals Actinides Series- all radioactive (mostly synthetic)

Magic seven Diatomic molecules= always exist as 2 of the same atoms bonded to each other H2H2 N2N2 O2O2 F2F2 Cl 2 Br 2 I2I2

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Color-Code the Periodic Table You can use any colors you want, just make a key on your personal periodic table On your personal periodic table color the following, every bullet has to be a different color: – Metalloids – Mercury and Bromine – The 7 Diatomics – Noble Gases – Transition Metals – Label groups 1,2,17, and 18 with the proper name

Liquids on the Periodic Table There are 2 liquids on the periodic table at STP Mercury is the only metal that is a liquid Bromine is the only nonmetal that is a liquid

Allotropes An allotrope is the same element that can be found in more than one different form – Graphite and Diamond are allotropes of Carbon – Dioxygen (O 2 )and Ozone are allotropes of Oxygen

Periodic Trends ELECTRONEGATIVITY ATOMIC RADIUS IONIC RADIUS IONIZATION ENERGY ELECTRON AFFINITY METALLIC CHARACTER MELTING AND BOILING POINT

The trend depends on 3 factors: 1.NUCLEAR CHARGE= atomic number= # of protons- the higher the nuclear charge the more the electrons are pulled toward the nucleus. 2.PRINCIPAL ENERGY LEVEL- Principal energy level is determined by the period an atom is located; the higher the principal energy level, the higher the potential energy, the larger the atom. 3.ELECTRON CLOUD SHIELDING EFFECT- inner electrons shield the outer electrons so they are less attracted to the nucleus so the atom is larger

Electronegativity A measure of the ability of an atom in a chemical compound to attract electrons. FLUORINE is the most electronegative atom on the Periodic Table PERIOD TREND: Electronegativity increases across a period (the closer to 8 valence electrons the more they will pull on the electrons) GROUP TREND: Electronegativity decreases down a group (the larger the atomic radius the less ability of that atom to attract electrons due to electron shielding)

Periodic Table of Electronegativities

Electronegativity Review Element with most Electronegativity: Element with least Electronegativity:

Atomic Radius Atomic radius = half of the distance between nuclei of identical atoms bonded together (bond radius). This is determined by how strongly an atom’s nucleus (positive charge) is attracted to its outermost electrons. PERIOD TREND: Radius decreases across a period Nuclear charge increases across a period so electrons are more closely attracted to the nucleus GROUP TREND: Radius increases down a group Addition of principal energy levels, so inner electrons shield outer electrons and the electrons are farther away from nucleus, so atom is larger.

Table of Atomic Radii

Review Ions Ions are formed when atoms gain or lose electrons Ions have a positive or negative charge Ionic Radii: The loss or gain of electrons by an atom causes a corresponding change in size.

Ionic Radii Cations Positively charged ions Smaller than the corresponding atom Metal tend to form CATIONS by LOSING an electron. Metal cations are smaller than their corresponding neutral atoms (they lost electrons). Anions Negatively charged ions Larger than the corresponding atom Nonmetals tend to for ANIONS by GAINING an electron. Nonmetal anions are larger than neutral atoms because they gained electrons.

Here is a simple way to remember a cation and an anion: This is a cat-ion. He’s a “plussy” cat! This is Ann Ion. She’s unhappy and negative. +

Ionic Radius Review The loss or gain of electrons by an atom causing a corresponding change in size. Metals Tend to ____ their valence electrons. What happens to their valence electrons?__________ Before: After: Therefore the atomic radius of metals is ___________ than their ionic radius.

Ionic Radius Review The loss or gain of electrons by an atom causing a corresponding change in size. Nonmetals Tend to _________ electrons. What happens to their radius?__________ Before: After: Therefore the atomic radius of nonmetals is ________________ than their ionic radius.

Table of Atomic Radii and Ionic Radii

Ionic Radius Metals form CATIONS Loss of electron Get a Positive Charge Radius Decreases when it becomes an ion Nonmetals Form ANIONS Gain of electron Get a Negative charge Radius Increases when it becomes an ion

Do Now Period 2: Li Be C N O F Ne Which elements do not want to lose their electrons? ____________

Ionization Energy Ionization energy = the energy required to remove an electron from an atom A + ionization energy  A + + e - PERIOD TREND: Tends to increase across a period – Within same principle energy level: due to increased nuclear charge the electrons are more closely attracted to nucleus GROUP TREND: Tends to decrease down a group – Addition of principle energy levels, so outer electrons are farther from the nucleus due to electron shielding, so less attracted to the nucleus

Another Way to Look at Ionization Energy

Ionization of Magnesium Ionization energy increases for successive electrons taken from the same atom Mg kJ  Mg + + e- Mg kJ  Mg 2+ + e- Mg kJ  Mg 3+ + e-

Ionization Energy Review Element with the most Ionization Energy: Element with the least Ionization Energy: Why do noble gases have such high ionization energy but no electronegativity?

Electron Affinity The energy change that occurs when an electron is acquired by a neutral atom is called the atom’s electron affinity. A + e-  A- + energy A + e- + energy  A- (unstable) PERIOD TREND: Tends to increases across a period – due to increasing nuclear charge (remember: the Halogens gain electrons most readily) GROUP TREND: Tends to decrease down a group – due to increasing electron shielding from addition of principle energy levels

REACTIVITY METALS- most reactive in lower left corner NONMETALS- most reactive in top right corner

Reactivity Review: Place the following elements in increasing order of reactivity: (least reactive first) – Sodium, potassium, calcium

Metallic Character As you go down a group, the metallic character ________________. As you go across a period, the metallic character ________________.

MELTING POINT AND BOILING POINT Trends for melting point and boiling point for elements are found on Table S. Metals tend to have higher melting points than nonmetals Nonmetals have lower boiling points than metals

Summation of Periodic Trends Electronegativity

Periodic Trends DefinitionTrend in PeriodTrend in Group ElectronegativityThe measure of the ability of an atom in a chemical compound to attract electrons Increases across a period Decrease down a group Atomic RadiusHalf the distance between nuclei of identical atoms bonded together Decreases across a period Increases down a group Ionization Energy The energy required to remove an electron from an atom Increases across a period Decreases down a group