The Periodic Table and Atomic Structure Section 2.1

Review Four classical atomic models Quantum Mechanical Model

Objectives Distinguish between metals, non-metals, and metalloids in terms of distinguishing properties Explain the structure of the periodic table Identify important families and elements Describe atomic theory in terms of subatomic particles and location (nucleus, energy levels) Define atomic number, mass number, isotope, and atomic molar mass and be able to identify these for a given element Determine numbers of protons, neutrons and electrons for a given element Describe the process of ionization and formation of cations and anions Identify patterns in the periodic table for valence electrons and energy levels Relate ionization to the octet rule

Law of Conservation of Mass Antoine Lavoisier Mass is neither created or destroyed The total mass of the reactants equals the total mass of the products

The Elements 115: basic building blocks 90 naturally occurring, 25 synthetic Split into 3 classes Metals Non-metals Metalloids https://www.youtube.com/watch?v=GFIvXVMbII0

Metals Most elements (75%) Silver/grey and shiny Conductors of heat and electricity Malleable and ductile Most solid at room temperature Reactivity varies Most reactive is francium (left and down) Inert= unreactive

Non-Metals 17 elements Grouped based on their different from metals Vary is state, color and reactivity Highly reactive= fluorine (right and up Inert= noble gases About half will appear at molecules (more than one atom)

Metalloids Remaining elements Properties intermediate between metals and non-metals Along the staircase (except aluminium) Ex. Silicon, arsenic, boron

The Periodic Table

The Periodic Table Organizes elements based on chemical properties Metals on left side and centre Non-metals on far right Exception hydrogen (learn more later) Metalloids between two Shows name and symbol for element Get to know the symbols! http://periodictable.com/

The Element Game For the following, identify as being a metal, non-metal or metalloid Hydrogen Sulfur Calcium Tin Gold Boron Aluminum Xenon

Pre-test For the following, give the element’s name or symbol: Calcium Hydrogen Sulfur Phosphorus Mg Na

Important Families/ Groups Vertical columns Groups of elements with similar chemical/physical properties Group 1: alkali metals Soft, shiny, silver, very reactive with water Compounds white and soluble in water Group 2: alkali earth metals Shiny, silver White compounds but not as soluble

Important Families cont… Group 17: halogens Non-metals Very reactive React with alkali metals to make salts Group 18: noble gases Very unreactive

Periods Horizontal rows Have the same number of levels of electrons

To Do Crossword What’s in a Name? ELEMENTary My Dear Watson

Atomic Theory Atoms are very small (10-10 m in diameter) What are three kinds of subatomic particles? Protons, Neutrons and Electrons Where are they found? Protons and Neutrons- inside the nucleus Electrons- outside the nucleus Protons and neutrons are over 99.9% of total mass Imagine this: our classroom filled with iron. If we take out the nuclei for all the iron atoms and place them side by side, they would be as big as a period in a book. But that period would almost equal the mass of the room full of iron

Protons Has a positive charge (p+) Mass of 1.67x10-27 kg The number of protons defines the element and is called the atomic number All helium atoms have a 2 p+ and every atom with 2 p+ is helium

Neutrons No charge (n0) Mass of 1.67x10-27 kg The number of protons and neutrons together make the atomic mass of the atom If an atom has 8 protons and 10 neutrons, its atomic mass is 18 If an element has an atomic number of 24 (protons) and an atomic mass of 52 (protons and neutrons) it has 28 neutrons

Electrons Charge of 1- (e-1) Mass of 9.11x10-31kg Electrons are so small that they are not factored into the atomic mass In an atom the number of protons = the number of electrons

Atomic Number Number of protons Determines the element Can you find the atomic number of the following elements? Pb Hg tin chlorine platinum Cu manganese lithium As we move through the periodic table, what do you notice about the ordering of atomic numbers?

Mass Number and Isotopes Isotope- atoms of same element with different number of neutrons Ex. Common form of hydrogen has one proton and no neutrons. 1/10 000 hydrogen atoms have a neutron, called deuterium (“heavy” hydrogen) Each isotope given a mass number Equals total number of protons and neutrons (don’t include electrons- too small) # of neutrons= mass number – atomic number

Mass Number and Isotopes cont… Can be shown as: Mass number element symbol atomic number Ex. Oxygen-16 What would be the symbols for oxygen-17? Oxygen- 18?

Mass number and isotopes Name: #p = _____ #n = _____ #e = _____ Name: #p = _____ #n = _____ #e = _____

Practice: Fill in the chart! Element Name Mass Number Number of Protons Number of Neutrons calcium 41 uranium 238 aluminum 14 9 5 20 10 iron 30

Atomic Molar Mass Shown in the periodic table Average mass of element’s isotopes Number of electrons equals number of protons (in neutral atoms) Atomic molar mass

Bohr Model of the Atom Neils Bohr- proposed that electrons moved around a nucleus at a specific fixed distance Energy level Electrons could move up levels by absorbing energy Electrons could move down levels by losing energy BUT each energy level can only have a certain maximum number of electrons

Energy Levels Electrons occupy energy levels Region around nucleus either empty or contain electrons Increase energy when get further from the nucleus Specific number of electrons/level First level- 2 electrons Next levels- 8 electrons Energy level can be empty, partly or completely filled

Drawing Atoms Drawings include: Ex. Hydrogen Lithium Sodium Oxygen Number of protons (in nucleus) Number of neutrons (in nucleus) Electrons in correct energy levels (how many electrons can be in each level?) Ex. Hydrogen Lithium Sodium Oxygen Sulfur Helium Neon Argon Calcium

Valence Electrons Electrons in the outermost energy level Valence number- number of electrons an element can lose/gain to combine with other elements How many valence electrons do each of the following elements have? Oxygen? Magnesium? Chlorine? Argon? Carbon-14?

The Octet Rule For understanding how atoms bond Atoms want to have eight electrons in their valence shell (which shell is this?) More stable when have full energy levels What are these elements like with full energy levels? Noble gases! Gain/lose electrons to be like their closest noble gas Ex. Chlorine will gain one electron to be like argon Exception: hydrogen, lithium and beryllium. Why? Who do they want to be like?

What Now? When we gain/lose electrons from an atom, what happens to its charge? Ex. Fluorine gains one electron to fill its outer octet. What is its electrical charge now? Gaining/losing electrons process called ionization Results in positively charged or negatively charged ions

Formation of Ions Elements can lose or gain outermost (valence) electrons Called ionization Makes ions (positively or negatively charged) Allows metals and non-metals to form compounds http://www.youtube.com/watch?v=xTx_DWboEVs&f eature=related

Cations Positively charged ions Metal ion loses electrons Where do the electrons go? To another atom Why would the atom be positively charged if it loses electrons? Ex Magnesium Loses 2 electrons What would the diagram look like before? After ionization? Put charge as a superscript: ex. Mg2+

Anions Negatively charged ions Non-metal gains electrons Where do the electrons come from? From atoms that lose electrons (cations) Why is it negatively charged? Ex. Oxygen Gains two electrons What is the diagram before? After ionization? How would you write it as a symbol?

Naming Ions Cations: Anions: Element name + ion Ex. sodium ion Ex. magnesium ion Anions: First part of element name and change ending to “ide” Ex. nitride Ex. oxide Ex. fluoride

Practice For each of the following ions, draw with nucleus and electrons and give appropriate name or symbol: Hydrogen ion Cl- Nitride Be2+ sulfide

Ion Trends in Periodic Table group 1 = 1+ group 2 = 2+ group 3-12 labeled on table group 15 = 3- group 16 = 2- group 17 = 1- group 18 not ions B, C, Si do not form ions

Why form ions? Why do atoms gain or lose electrons? To have full energy levels and be more stable like closest noble gas Once ions are formed: Electrically charged What would happen when I bring a cation and an anion together? Form a bond! How we make compounds between metals and non-metals Need to form the ion first before a bond can be formed

TO DO Building an Atom Assignment