What is Matter? n/cells/scale/ n/cells/scale/

What is Matter? Any thing that occupies space (volume) and has mass Can be visible or invisible to the naked eye All matter is composed of atoms

Atomic Size At sea level, one cubic centimeter of air (size of a sugar cube, or marble) will have 45 billion billion atoms within it.  45,000,000,000,000,000,000 How many atoms would it take to fill a universe?

Count to 45,000,000,000,000,000,000 Fill Lincoln high school COMPLETELY with marbles. Empty and re-fill it once a MINUTE (24 hours per day). After 400,000 years, you would have 45,000,000,000,000,000,000.

1.All substances are made from atoms. 2.There are about 100 different types of atoms 3.An element is a substance which contains only one type of atom Atoms Atoms

S.MORRIS 2006 This Powerpoint is hosted on Please visit for 100’s more free powerpoints

HISTORY OF THE ATOM 460 BC Democritus develops the idea of atoms he pounded up materials in his pestle and mortar until he had reduced them to smaller and smaller particles which he called ATOMA (greek for indivisible)

HISTORY OF THE ATOM 1808 John Dalton suggested that all matter was made up of tiny spheres that were able to bounce around with perfect elasticity and called them ATOMS

HISTORY OF THE ATOM 1898 Joseph John Thompson found that atoms could sometimes eject a far smaller negative particle which he called an ELECTRON

HISTORY OF THE ATOM Thompson develops the idea that an atom was made up of electrons scattered unevenly within an elastic sphere surrounded by a soup of positive charge to balance the electron's charge 1904 like plums surrounded by pudding. PLUM PUDDING MODEL

HISTORY OF THE ATOM 1910 Ernest Rutherford oversaw Geiger and Marsden carrying out his famous experiment. They fired Helium nuclei at a piece of gold foil which was only a few atoms thick. They found that although most of them passed through. About 1 in 10,000 hit

HISTORY OF THE ATOM gold foil helium nuclei They found that while most of the helium nuclei passed through the foil, a small number were deflected and, to their surprise, some helium nuclei bounced straight back. helium nuclei

HISTORY OF THE ATOM Rutherford’s new evidence allowed him to propose a more detailed model with a central nucleus. He suggested that the positive charge was all in a central nucleus. With this holding the electrons in place by electrical attraction However, this was not the end of the story.

HISTORY OF THE ATOM 1913 Niels Bohr studied under Rutherford at the Victoria University in Manchester. Bohr refined Rutherford's idea by adding that the electrons were in orbits. Rather like planets orbiting the sun. With each orbit only able to contain a set number of electrons.

Bohr’s Atom electrons in orbits nucleus

HELIUM ATOM (atomic structure) + N N proton electron neutron Shell What do these particles consist of?

ATOMIC STRUCTURE Particle proton neutron Charge -ve charge 1 1 / 1000 Mass

ATOMIC STRUCTURE the number of protons in an atom the number of protons and neutrons in an atom He 2 4 Mass number Atomic number number of electrons = number of protons Number of neutrons = mass nnumber – atomic number

ATOMIC STRUCTURE Electrons are arranged in Energy Levels or Shells around the nucleus of an atom. first shella maximum of 2 electrons second shella maximum of 8 electrons third shella maximum of 8 electrons

ATOMIC STRUCTURE There are two ways to represent the atomic structure of an element or compound; 1.Electronic Configuration 2.Atom Diagrams

ELECTRONIC CONFIGURATION With electronic configuration elements are represented numerically by the number of electrons in their shells and number of shells. For example; N Nitrogen in 1 st shell 5 in 2 nd shell Electron configuration = 2, = 7 Has 7 protons so 7 electrons

ELECTRONIC CONFIGURATION Write the electronic configuration for the following elements; Ca O ClSi Na B 11 5 a)b)c) d)e)f) 2,8,8,22,8,1 2,8,72,8,42,3 2,6

DOT & CROSS DIAGRAMS With Dot & Cross diagrams elements and compounds are represented by Dots or Crosses to show electrons, and circles to show the shells. For example; Nitrogen N XX X X XX X N 7 14

DOT & CROSS DIAGRAMS Draw the Dot & Cross diagrams for the following elements; OCl a)b) O X X X X X X X X Cl X X X X X X X X X X X X X XX XX

SUMMARY 1. The Atomic Number of an atom = number of protons in the nucleus. 2. The Atomic Mass of an atom = number of Protons + Neutrons in the nucleus. 3. The number of Protons = Number of Electrons. 4. Electrons orbit the nucleus in shells. 5. Each shell can only carry a set number of electrons.

1.Isotopes are atoms of the same element that have different numbers of neutrons (e.g. carbon-12 and carbon- 14) 2.Isotopes have the same atomic number but different mass numbers Isotopes Isotopes

Isotopes

What is an Ion? An ion is a charged atom (or particle) and can be either positively or negatively charged. Atoms can become ions by either gaining or loosing electrons from their outer shell.

These electrons in the outer shell are called Valence Electrons. The charge and number depends on how many valence electrons are gained or lost.

Where do these gained electrons come from? How do metals loose electrons? These electrons are gained from metals trying to loose their valence electrons trying to become ions. Therefore, for elements to become ions there must be other elements present to either accept or give away electrons. If two ions join together we can form c_______.