Chapter 10 Atomic Structure and the Periodic Table

Objectives 10.1 List the names and symbols of common elements (Self Quiz) 10.1 Describe the present model of the atom 10.1 Describe how electrons are arranged in an atom 10.2 Identify quarks as particles of matter that make up protons and neutrons

Objectives 10.2 Explain how particle accelerators are used to study particles within atoms 10.3 Compute the atomic mass and mass number of an atom 10.3 Identify and describe isotopes of common elements 10.3 Interpret the average atomic mass of an element 10.3 Determine the number of protons, neutrons, and electrons an atom has from its symbol

Chemical Symbols Every element has a unique one or two letter abbreviation. Some elements symbols come from their Latin word (Aurum = Au = Gold) Next week’s quiz, need to memorize 20 elements and symbols (your choice) – Choose wisely

Objectives 10.4 Describe the periodic table of elements and use it to find information about an element 10.4 Distinguish between a group and a period 10.4 Use the periodic table to classify an element as a metal, non-metal, and metalloid 10.4 Identify families on the periodic table 10.4 Use the periodic table to determine the number of valence electrons

Matter – Composed of Atoms – Composed of A Positive Nucleus Negative Electrons Orbiting the Nucleus

Protons Have a Positive Charge – A +1 Charge Have a mass of 1 AMU – Atomic Mass Unit Found in the Nucleus The Atomic Number is the number of Protons an element has – On periodic table, the whole number integer (no decimals)

Neutrons Have a neutral charge Have a mass of 1 AMU Found in the Nucleus An atom’s mass is equal to the number of Protons + the number of Neutrons – An element has 6 protons and 7 Neutrons. Its Atomic Mass would be 13 On periodic table, the Average Atomic Mass is Given (the number with decimals)

Electrons Have a negative charge – A -1 Charge Have a mass of 0 AMU – No Mass! As far as we are concerned, they weight approx 1/2000 th of the mass of a proton. Might as well be nothing Found orbiting the nucleus Neutral Atoms have EQUAL number of protons and electrons

Bohr’s model of Atom Electrons orbit the nucleus in “shells” Only certain amount of electrons per shell 1 st Shell: 2 Electrons 2 nd Shell: 8 Electrons 3 rd Shell: 18 Electrons 4 th Shell: 32 Electrons

Electron Cloud Shells called electron clouds – Since electrons move very quickly, hard to know where they are (and Heisenberg Uncertainty principle). Instead, pictures often show a cloud. Cloud represents an allowed area to orbit for the electron, with roughly a 90% chance of finding the electron

Valence Electrons How many outermost electrons? Maximum Number of

Are atoms the smallest? Protons and Neutrons are composed of Quarks – Quarks are the building blocks of atoms nuclei – 3 Quarks per Proton and Neutron – Electrons don’t have any quarks – How much deeper does the rabbit hole go?!

Atomic Mass Atomic Mass: Protons + Neutrons – Individual Atoms will have a whole number integer mass – The Atomic Mass on Periodic Table is an average – Not all atoms of the same element have the same mass. They differ in neutrons These are called Isotopes – Carbon – 12 and Carbon – 14 are both chemically Carbon, but weight different amounts

Br Ar Ca e–e– n0n0 p+p+ MassAtomic

Practice Q’s – Which atom(s) have 6 Neutrons? – Which atom(s) have an odd number of neutrons? – Which atom(s) have more neutrons than protons? – The ?? Is an isotope of which other atom? – Which atom(s) have 6 electrons?

Historical Perspective Mendeleev organized the periodic table (same guy who did the punnett square) Really smart guy, left blanks in where he thought that another element would be discovered and predicted the properties of the element

Development of Periodic Table Mendeleev, for instance, predicted the discovery of germanium (which he called eka-silicon) as an element with an atomic weight between that of zinc and arsenic, but with chemical properties similar to those of silicon.

Historical Perspective The periodic table is organized by groups. Each group has similar properties (vertical columns) – Oxygen is similar to Sulfur is similar to Selenium This is all because of having similar valence electron configurations (same outer shell)

Mendeleev’s table

Development of Periodic Table Elements in the same group generally have similar chemical properties. Properties are not identical, however.

Development of Periodic Table Dmitri Mendeleev and Lothar Meyer independently came to the same conclusion about how elements should be grouped.

Key Terms 10.4 Metal Nonmetal Metalloid Semiconductor – Conductor – Insulator Transition Elements Lanthanide Actinide Alkali Metals Alkaline Earth Metals Halogens Noble Gases

Periodic Table

Metals

Properties of Metals Luster Conductors (Heat/Electrons) Malleable Ductile Most are solid at room temperature Loosely held valence electrons

Nonmetals

Properties of Nonmetals Insulators Brittle Dull Many are gases at room temperature Tightly held valence electrons

Semi-metals or Metalloids

Metalloids Have properties of both – Instead of thinking an element is purely a metal or only a nonmetal, think of the periodic table as a spectrum. – Lower left is the best metal, as you move towards the top right, you lose your metal properties and become more of a nonmetal – Metalloids are in the middle – What metal and nonmetal properties does Gold have?

Properties of Metal, Nonmetals, and Metalloids

Alkali Metals One Word: First Column

Alkaline Earth Metals Two Words: Second Column

Halogens (Name: Salt Maker)

Noble Gases (Inert Gases)

Lanthanide and Actinide

Transition Metals