Atoms 0 Matter is anything that takes up space and has mass. http:// - PowerPoint PPT Presentation

The Element Song Atoms 0 Matter is anything that takes up space and has mass. http:// All matter is made of atoms. 0 Atoms are the basic building blocks of matter. They www.privatehand.com/ make up everything around us; Your desk, the board, your body, everything is made of atoms! flash/elements.html 0 Atoms are too small to see without powerful microscopes. Atomic Structure Subatomic Particles There are two basic components in every atom: Three subatomic particles make up every atom: Subatomic Particle Charge Location Electron Cloud Proton Positive (+) Nucleus or “Core” Neutron No Charge (0) Nucleus or “Core” Nucleus Electron Negative (-) Electron Cloud

Subatomic Particles Atomic Theory Changes over time… Electron Cloud: • Electrons orbit the nucleus. Nucleus or “Core”: • Protons and Neutrons are found in the nucleus. Democritus Atomic Theory ■ 460 BC - Greek philosopher proposes 0 Because we cannot see atoms, we use models to teach and learn about atoms. the existence of the atom 0 The atomic theory has changed over time as new technologies have become available. ■ He pounded materials until he made them into smaller and smaller parts 0 Remember: Scientific knowledge builds on past research and experimentation. ■ He called them atoma which is Greek for “indivisible”. http:/ /s3.timetoast.com/public/uploads/photos/1765183/democritus.png?1316996277

Atomic Theory Timeline Democritus ■ His Theory: Scientist Information Model All atoms: John All matter is made of atoms. ■ Are small hard particles Dalton Atoms are too small to see, indivisible and ■ Are made of a single material formed into indestructible. All atoms of a different shapes and sizes given element are identical. ■ Are always moving, and they form different materials by joining together John Dalton John Dalton ■ His Theory: ▪ All substances are made of atoms that cannot be created, divided, or destroyed. ■ 1803 - British chemist; elements combine ▪ Atoms join with other atoms to make new in specific proportions to form compounds substances. ▪ Atoms of the same element are exactly alike, Solid Sphere Model or and atoms of different elements are different in Bowling Ball Model mass and size. Proposed by John Dalton http:/ /a5.files.biography.com/image/upload/c_fit,cs_srgb,dpr_1.0,h_1200,q_80,w_1200/MTE1ODA0OTcxNTk5OTU1NDY5.jpg

Atomic Theory Timeline Dimitri Mendeleev (Men-da-lay-ev) Scientist Information Model Discovered the negative electron, and predicted that J.J. Thompson ■ In 1869 Russian chemist Dimitri Mendeleev there also must be a positive started the development of the periodic particle to hold the electrons in place. table, arranging chemical elements by atomic mass. He predicted the discovery of other elements, and left spaces open in his periodic table for them. http:/ /a5.files.biography.com/image/upload/c_fit,cs_srgb,dpr_1.0,h_1200,q_80,w_1200/MTE5NTU2MzE2MzEzMDYwODc1.jpg J.J. Thomson J.J. Thomson ■ His Theory: ■ Atoms contain negatively charged particles ■ 1897 - English chemist and physicist; called electrons and positively charged matter. discovered 1 st subatomic particles ■ Created a model to describe the atom as a Plum Pudding Model or sphere filled with positive matter with negative particles mixed in Raisin Bun Model Proposed by J.J. Thomson ■ Referred to it as the plum pudding model https:/ /media1.britannica.com/ eb-media/85/101085-004-E1192912.jpg

Atomic Theory Timeline Ernest Rutherford Scientist Information Model Ernest Discovered the nucleus of an atom ■ 1912 - New Zealand physicist discovered Rutherford and named the positive particles in the nucleus the nucleus “protons”. Concluded that electrons are scattered in empty space around the nucleus. Nuclear Model Proposed by Ernest Rutherford https:/ /historyoftheatom.files.wordpress.com/2015/02/ ernest-rutherford.jpg Ernest Rutherford ■ His Theory: ▪ Small, dense, positively charged particle present in nucleus called a proton ▪ Electrons travel around the nucleus, but their exact places cannot be described. ▪ Conducted the Gold Foil Experiment https:/ /sakai.ithaca.edu/access/content/user/jkleingardner/principles%20html%20slides/img/ch1/GoldFoil.jpg

Atomic Theory Timeline Niels Bohr ■ 1913 - Danish physicist; discovered Scientist Information Model energy levels Neils Concluded that electrons are Bohr located in planet-like orbits around the nucleus in certain energy levels. Bohr Model or Planetary Model Proposed by Niels Bohr http:/ /www.azquotes.com/picture-quotes/ quote-a-physicist-is-just-an-atom-s-way-of-looking-at-itself-niels-bohr-3-7-0770.jpg Niels Bohr Erwin Shrodinger ■ 1924 - Austrian physicist; developed the ■ His Theory: ▪ Electrons travel around the nucleus in definite electron cloud model paths and fixed distances. ▪ Electrons can jump from one level to a path in Electron Cloud Model another level. Proposed by Erwin Schrodinger

Erwin Shrodinger Atomic Theory Timeline ■ His Theory: Scientist Information Model ▪ The exact path of electrons cannot be predicted. Neutrons James Discovered that neutrons were also ▪ The region referred to as the electron cloud, Chadwick located in the nucleus of an atoms and that they contain no charge. is an area where electrons can likely be found. James Chadwick Scientist Information Model (Many Scientists!) Electrons do not orbit the ■ 1932 - English physicist; discovered The Modern nucleus in neat planet-like Atomic Theory neutrons orbits but move at high speeds in an electron cloud ■ His Theory: around the nucleus. ▪ Neutrons have no electrical charge. ▪ Neutrons have a mass nearly equal to the mass of a proton. ▪ Unit of measurement for subatomic particles is the atomic mass unit (amu). http:/ /chadwicksphysics.weebly.com/uploads/1/7 /3/ 4/17347989/3729228_orig.jpg

Modern Theory of the Atom Modern Theory of the Atom ■ Atoms are composed of three main subatomic ■ The protons and neutrons are located within particles: the electron, proton, and neutron. the nucleus, while the electrons exist outside of the nucleus. ■ Most of the mass of the atom is concentrated in ■ In stable atoms, the number of protons is equal the nucleus of the atom. to the number of electrons. Modern Theory of the Atom Modern Theory of the Atom ■ The type of atom is determined by the number ■ The sum of the number of protons and of protons it has. neutrons in a particular atom is called the atomic mass. ■ The number of protons in an atom is equal to ■ Valence electrons are the outermost electrons. the atomic number.

Atom electron Proton Neutron www.thinkgeek.com/images/products/additional/large/periodic_magents_close.jpg Atom Neutrons Atomic Number = Protons Electrons number of protons Atomic Weight = number of protons + number of neutrons Nucleus Protons = Number of electrons //village.wsfcs.k12.nc.us/lv/hswest/hp.nsf/Files/ potassium6/$File/atomic+number.bmp Electron clouds

Hydrogen Halogens https:/ /www.youtube.com/watch?v=K5x7EOiQ1y0 Alkali Metals Noble Gases Alkaline Earth Metals H Atomic Weight = Transition Metals number of protons + 19 number of neutrons K 39.0938 = 19 + neutrons -19 -19 20.0938 neutrons Potassium There cannot be 0.0928 of a Inner Transition 39.0938 neutron, so this number is rounded Metals to 20 neutrons . by Daniel R. Barnes, init: 11/03/2005 Hydrogen Halogens Hydrogen Halogens http://www.youtube.com/watch?v=DFQPnHkQlZM Alkali Metals Alkali Metals Noble Gases Noble Gases Alkaline Earth Metals Alkaline Earth Metals NONMETALS H He H He Transition Metals Transition Metals Be F Be F Li Ne Li Ne metalloids Na Mg Na Mg Cl Ar Cl Ar Br Br K Ca Kr K Ca Kr METALS Rb Sr Xe Rb Sr Xe I I Cs Ba At Rn Cs Ba At Rn Fr Fr Ra Ra Inner Transition Inner Transition Metals Metals by Daniel R. Barnes, init: 11/03/2005 by Daniel R. Barnes, init: 11/03/2005

Hydrogen Halogens Metalloids = Semimetals Alkali Metals Noble Gases (These words may mean something slightly Alkaline Earth Metals different from each other.) Metals H He Transition Metals Be B F Li Ne Na Mg Si Cl Ar • Metals are lustrous As Br K Ca Ge Kr (shiny), malleable, ductile, and are good Te Rb Sr Sb Xe I conductors of heat and Cs Ba At Rn electricity. Fr Ra • They are mostly solids at room temp. • What is one exception? Inner Transition Metals by Daniel R. Barnes, init: 11/03/2005 Nonmetals Metalloids • Metalloids, aka semi-metals • Nonmetals are the are just that. opposite. • They have characteristics of • They are dull, brittle, both metals and nonmetals. nonconductors • They are shiny but brittle. (insulators). • And they are semiconductors. • Some are solid, but • What is our most important many are gases, and semiconductor? Bromine is a liquid.

• Each row is called a “period” • The elements in each period have the same number of shells Adapted by J. Phillips Written by Liz Rosawww.middleschoolscience.com 2008 All images are from www.Chem4kids.com www.chem4kids.com Except for He, it • Transition Metals has 2 electrons have slightly different rules for • Each column is called shells and valence a “group” electrons. • Each element in a group has the same number of electrons in • This is something their outer orbital, also you will learn about known as “shells”. in High School Chemistry. • The electrons in the outer shell are called “valence electrons” www.chem4kids.com www.chem4kids.com