Chapter 10 Notes Atomic Structure & The Periodic Table

Atomic Structure Element - only one kind of atom - Cannot be further broken down ex- Pb, Cu, Ne, He, H, O, C Periodic Table-Table of 114 elements know to man -90 naturally occurring Earth -24 artificially made in labs

The ATOM Smallest part of an element Still has properties of that element Greeks atomos = indivisible

4 models: Dalton solid sphere/indestructible -element made of same atoms

Thompson chocolate chip cookie/plum pudding -sphere + charge -in sphere - charges=electron

Rutherford/Bohr solar system model -dense center = nucleus -nucleus +charge - -charged particles orbit nucleus

Present Model nucleus + charged particles = proton -nucleus 0 charged particles = neutrons -cloud – charged particles = electrons constantly moving Electron Cloud

Drawing Atomic Models Electron Cloud-area where electrons move speed of light - electron levels ex/2, 8, 18, 32 …. Level 1: 2e- Level 2: 8e- Level 3: 18e- Nucleus Protons p+ Neutrons, n

atomic # = p + = e - mass # - atomic # = n 0 atomic mass = avg of all isotopes 4 Be Beryllium Atomic number Symbol Element name Atomic mass

Isotopes Atoms of the same element with different numbers of neutrons ex.Carbon normal C-12 (6 p + & 6 n 0 ) isotope C-14 (6 p + & 8 n 0 )

Periodic Table 1834 – 1907 Russian chemist Mendeleev arranged all elements known 1900 by mass Found patterns Predicted mass & properties of undiscovered elements Problems? atomic #s didn’t match up when arranged by properties New table – atomic #s match up

Valence electrons Electrons in the out most energy level of the atom Corresponds with the Period number on the periodic table Lewis dot diagrams illustrate the valence electrons Carbon has 4 valence electrons

Table Parts Period – horizontal row of the table Family/Group – vertical columns elements have similar properties

Group 1 – Alkali Metals Conduct heat & electricity Soft, low m.p. & low density React with acids Very reactive, never found as free elements Malleable, ductile, luster 1e- in outer energy level (+1 cation) Identified by flame test

Group 2 – Alkaline Earth Metals Highly reactive, never found free in nature Low density React with acids 2e- in outer energy level (+2 cation) Identified by flame test

Group 3 – 12: Transition Metals Common metal, properties vary High m.p. - react with acids Brittle, soft, strong, hard, malleable, ductile Alloys – mixture of 2 or more metals to gain desired characteristics cations Ores – mineral or other natural material from which one or more metals can be obtained

Groups 13 – 17: Nonmetals Insulators for electricity, dull, brittle Not reactive w/ acids Solids, liquids & gases React with metals to form compounds –Group 17: Halogens Form salts, all 3 room temp Toxic, different colors –Metalloids Properties of metal & nonmetals stairstep

Group 18 : Noble Gases Perfect elements 8 valence electrons Inert- not reactive

Diatomic Seven 7 elements that exist as 2 atoms combined together in nature –Hydrogen –Nitrogen –Oxygen –Fluorine –Chlorine –Bromine –Iodine

Chapter 12 Notes Elements & Properties

Metallic Bonding Not ionic or covalent Positively charged ions surrounded by “sea of electrons” Outer electrons move freely

Flame Tests Certain elements can be identified by the color of flame they produce

Transiton Elements Bright colors of gemstones Iron, cobalt & nickel = magnetic fields Copper, gold & silver = coins Mercurcy – room temp. Ores – metals in the Earths Crust

Synthetic Elements Made by combining existing elements w/ fast moving particles More than 92 protons = transuranium Unstable breakdown quickly

Radioactive Elements Nucleus breaks down giving off particles & energy Becomes other elements as the number of protons change

Nonmetals Diatomic 7 Less reactive further down the column Halogens & Noble gases Sublimation – solids change into vapors - ex. Iodine

Hydrogen Smallest element Uniquie properties – in a group of its own

Mixed Groups Semiconductors – conduct electric current under certain conditions Allotropes – different forms of the same element – Graphite & diamonds = carbon – O 2 & O 3 both are oxygen

Ozone = O 3 Oxygen molecule O 2