Intro to Chemistry Atomic Structure

What is an Atom Smallest division of PURE MATTER matter that still retains physical and chemical properties of that Matter Smallest division of PURE MATTER matter that still retains physical and chemical properties of that Matter First Proposed by the Greeks 2400 years ago: name means indivisible First Proposed by the Greeks 2400 years ago: name means indivisible

Atomic Structure Atoms have 2 regions Atoms have 2 regions Nucleus- center of the atom contains protons and neutrons Nucleus- center of the atom contains protons and neutrons Electron Cloud- empty space around atom which contains the electrons Electron Cloud- empty space around atom which contains the electrons

Nucleus: Center of the Atom Proton- + charged particle: Atomic Number Proton- + charged particle: Atomic Number Neutron- has NO charge Neutron- has NO charge Protons + Neutron= Atomic Mass of the element Protons + Neutron= Atomic Mass of the element

Electron Cloud Electron-smallest of the atomic particles; has no weight. Orbits around nucleus in electron cloud Electron-smallest of the atomic particles; has no weight. Orbits around nucleus in electron cloud

How the atom “works” Protons and Electrons “live” in the postively charged nucleus and make up the entire mass Protons and Electrons “live” in the postively charged nucleus and make up the entire mass Electrons are negatively charged and occupy a large amount of space surrounding the nucleus Electrons are negatively charged and occupy a large amount of space surrounding the nucleus

Atom “basics” Number of Protons = Number of Electrons Number of Protons = Number of Electrons Neutrons have no charge so their number can change without changing the element Neutrons have no charge so their number can change without changing the element Atomic Mass = # of Protons + # of Neutrons Atomic Mass = # of Protons + # of Neutrons

The Periodic Table Unit II—Part 4

The Father of the Periodic Table— Dimitri Mendeleev Mendeleev was the first scientist to notice the relationship between the elements Mendeleev was the first scientist to notice the relationship between the elements Arranged his periodic table by atomic mass Arranged his periodic table by atomic mass Said properties of unknown elements could be predicted by the properties of elements around the missing element Said properties of unknown elements could be predicted by the properties of elements around the missing element Moseley later discovered that the periodic nature of the elements was associated with atomic number, not atomic mass Moseley later discovered that the periodic nature of the elements was associated with atomic number, not atomic mass

The Periodic Table Column = Group or Family 18 columns on the Periodic Table Row = Period 7 rows on the Periodic Table

What does the information in the box tell me? 1H1.008 Atomic Number = # of protons (and electrons in its pure state) Atomic Mass = # of protons plus neutrons Elemental Symbol

Metals, Nonmetals, and Semi-metals Metals are to the left of the stair- step Only nonmetal on the metal side Nonmetals are on the right of the stair-step Semi-metals, “metalloids,” touch the stair-step

The Groups of the Periodic Table Group 1 or (IA): The Alkali Metals Group 1 or (IA): The Alkali Metals Most reactive metals on the PT Most reactive metals on the PT Rarely found free in nature Rarely found free in nature Charge of 1—1 valence electron Charge of 1—1 valence electron Group 2 (or IIA) : The Alkaline Earth Metals Group 2 (or IIA) : The Alkaline Earth Metals Still quite reactive Still quite reactive Charge of 2—2 valence electrons Charge of 2—2 valence electrons

T he Groups of the Periodic Table Groups 3-12: Transition Metals Groups 3-12: Transition Metals Found freely and in compounds in nature Found freely and in compounds in nature Charge is usually 2 but can vary—usually 2 valence electrons Charge is usually 2 but can vary—usually 2 valence electrons Group 13 (or IIIA): Boron Family Group 13 (or IIIA): Boron Family Charge is 3—3 valence electrons Charge is 3—3 valence electrons

The Groups of the Periodic Table Group 14 or (IVA): The Carbon Family Group 14 or (IVA): The Carbon Family Contains elements that can form unusual bonds (carbon and silicon) Contains elements that can form unusual bonds (carbon and silicon) Charge is +4 or -4—contains 4 valence electrons Charge is +4 or -4—contains 4 valence electrons Group 15 or (VA): The Nitrogen Family Group 15 or (VA): The Nitrogen Family Charge is -3—contains 5 valence electrons Charge is -3—contains 5 valence electrons

The Groups of the Periodic Table Group 16 (or VIA): The Oxygen Family Group 16 (or VIA): The Oxygen Family Also known as the chalcogens Also known as the chalcogens Charge is -2—6 valence electrons Charge is -2—6 valence electrons Group 17 (or VIIA): The Halogens Group 17 (or VIIA): The Halogens Most reactive nonmetals Most reactive nonmetals charge is -1—7 valence electrons charge is -1—7 valence electrons Group 18 (or VIIIA): The Noble Gases (The Inert Gases) Group 18 (or VIIIA): The Noble Gases (The Inert Gases) Nonreactive Nonreactive Charge is 0—2 or 8 valence electrons Charge is 0—2 or 8 valence electrons

Special Rows on the PT Lanthanides Actinides