Atoms and the Periodic Table

http://www.turbosquid.com/FullPreview/Index.cfm/ID/246735http://gpc.edu/~pgore/PhysicalScience/atom-with-electrons.gif

Matter and Atoms Everything made of matter Matter has mass and volume Matter made of atoms Atoms are building blocks of matter Atoms cannot be chemically divided (H bomb - atoms going through a nuclear rxn,

NOT a chemical rxn) Most matter made of compounds

Matter, Atoms, Compounds

Compound: made of 2 or more types of atoms Ex: water: H2O made of 2 hydrogen atoms and 1 oxygen

atom

Learn later how compounds form Elements: basic substances of matter

Element cannot be further broken down chemically Atom: smallest unit of an element that has the properties of

the element Ex: hydrogen is an element, hydrogen atom is smallest unit

of hydrogen you can find

Periodic Table of Elements Created by Dmitri Mendeleev

in 1869 He noticed pattern of

properties amongst elements when placed in order of atomic mass

This order made problems in the pattern

Today periodic table arranged by atomic number

This better reflects patterns of properties http://jscms.jrn.columbia.edu/cns/2006-04-18/fido-luxuriantflowinghair/mendeleev/asset_medium

Periodic Table of Elementshttp://www.dayah.com/periodic/

Neon

http://www.oneillselectronicmuseum.com/page9.html

Iodine

http://img.alibaba.com/photo/50296091/Iodine.jpg

Sodium

http://www.vanderkrogt.net/elements/images/sodium.jpg

Iron

http://mineral.galleries.com/minerals/elements/iron/iron.jpg

Sulfur

http://www.geocities.jp/senribb/jewels/Sulfur.jpg

Copper

http://gwydir.demon.co.uk/jo/minerals/pix/copper1.jpg

Boron

http://www.theodoregray.com/PeriodicTableDisplay/Samples/005.1/s9.JPG

Periodic Table of the Elements

Named periodic table b/c it’s periodic Regular repeating pattern in its arrangement

Today it has many more elements than in 1869

New discoveries = new elements Atom is smallest whole unit of element

Organization of Periodic Table

Vertical column = family or group Elements in group have similar chemical and

physical properties Horizontal row = period Sides of table = main elements Middle of table = transition elements

Organization of Periodic TableOutline metals, nonmetals, metalloids (different colors)

http://www.solpass.org/6-8Science/8s/Standards/periodic%20table.JPG

Organization of Periodic Table

Metals: solids (except mercury), ductile, malleable, conduct electricity, can make an alloy (combo of metals)

Nonmetals: some solids, some liquid, some gas, most do not conduct electricity

Metalloids: along “staircase”, hard to classify, properties of metal and nonmetal

Periodic Table Atomic symbol (ex. H =

hydrogen) Atomic mass = number or

protons & neutrons Atomic # = number of protons Na = sodium, Na is 11 so 11

protons; 23 -11 = 12 so 12 neutrons

Atom electrically neutral (# protons = # electrons) Ex Na has 11 protons and 11

electrons

http://education.jlab.org/glossary/atomicnumber.html

Periodic Table Row = period

Period ends when highest energy level is full or 8 e-

Noble gases: stable electron config., inactive/inert,

Halogens: group #17, 7 valence e-, like to gain 1 electron to be happy

Alkali metals: group #1, 1 valence electron, usually lose it to be stable

Atoms and Electrons Atoms

Nucleus w/ protons & neutrons Electrons orbit nucleus

Bohr found electrons move around nucleus Electron found in energy level Each energy level has different

amount of energy http://education.jlab.org/qa/atom_model_03.gif

Atoms & Electrons Each energy level can only hold specific number of

electrons Level 1: 2 e- Level 2: 8 e- Level 3: 18 e- Level 4-7: 32 e-

Valence electron: found in highest energy level (shell) electrons loosely held by nucleus Determine how atom reacts/bonds w/ another atom Determine chemical properties & reactivity of element

Atoms and Electrons Core electrons: electrons found in inner

shells/energy levels Valence electrons - occupy outermost shell/energy

level Electrostatic force: bonding force that holds 2 or

more atoms together b/c electrons are rearranged between the atoms

Main group elements: group number = number of valence electrons Elements in same group have same number of valence e- Elements in same group have similar properties b/c same

valence e-

Atoms and Electrons Bohr model: shows number of

energy levels and number of valence electrons

Doesn’t work for transition elements (we will learn why later)

Ex: Na (sodium) Group 1 so 1 valence e-

K (potassium) (draw model out)

Sodiumhttp://homepages.ius.edu/GKIRCHNE/BohrNa.jpg

Atoms and Electrons Energy levels want to be full If can’t be full - better to have 8 e- in shell to

be stable 8 e- in last shell = stable electron

configuration; less likely to react Noble gases (group 18) 8 valence e- and

inert (do not react) Ex. B (boron) Ex. Calcium (Ca)

Stable Electron Configuration

Full energy level = stable 8 e- in outer shell = stable Atom can do 2 things to become stable

1) give away electrons in outer shell 2) take electrons from other atoms who need to

give the electrons up to be stable

Gaining/Losing electrons to become stable allows atoms to chemically react/bond w/ other atoms

Atoms must be stable to be happy!

Periodic table and electrons

Halogens: group #17, 7 valence e-, like to gain 1 electron to be happy

Alkali metals: group #1, 1 valence electron, usually lose it to be stable

Bonding Bonding has to do w/ valence e- Metal: reactivity depends on gaining/losing

electrons Depends on how tightly atom holds its

valence e- Easier to gain or lose?

Less than 4 valence - easier to lose, takes less energy

5 or more valence - atom holds onto e- and gets more from another atom to fill its shell and be stable