What is Chemistry? SIMPLY PUT, IT’S THE STUDY OF THE COMPOSITION, PROPERTIES AND BEHAVIOUR OF MATTER

Matter: Properties and Changes  Matter is anything that has mass and takes up space.(e.g. your desk)  Matter is described by its features or Properties.  Physical Properties describe how matter appears or anything that can be observed without forming a new substance. (e.g. colour)  Chemical Properties describes the characteristics of how matter reacts, or fails to react, making a new substance. (e.g. flammable)  A Physical Change occurs when no new substance is formed. (e.g. ice melting / water freezing)  A Chemical Change on the other hand, produces a new substance (e.g. sodium chloride, table salt)

The Classification of Matter

Mixtures and Pure Substances  A Pure Substance is matter made solely of one kind of material. (e.g. distilled water)  A Mixture is made of more than one pure substance. (e.g. toothpaste)  Heterogenoeus or Mechanical Mixtures are formed by two or more visible parts. (e.g. salad)  Homogenous Mixtures or Solutions occur when one substance dissolves into another and appears as one. (e.g. sugar water)

Elements and Compounds  Elements are pure substances that are not easily broken down (e.g. hydrogen)  All Elements are made of tiny units called atoms. Atoms have smaller charged particles called Protons (+), Electrons (-) and Neutrons (+/-)  Protons and Neutrons are found in the Nucleus of the item and the Electrons move around the nucleus in specific orbits. The first ring around the nucleus is limited to 2 electrons, followed by 8 in the second, third, and so forth. Elements are most stable with 8 electrons in their outer valence (e.g. Noble gases)  Bohr-Rutherford Diagrams are used to show the number and specific arrangement of electrons in an element.  Compounds is a pure substance that is made of 2 or more elements in a particular ratio (e.g. Sodium Chloride Na + + Cl - → NaCl )

The Periodic Table

The Table Divided  The elements in the periodic table are arranged by atomic number.  Rows are called periods.  Columns are called groups or families. They share a common electron valence.  If expressed in standard notation as in the sodium atom below, along with the symbol (Na) and common Ionic charge (+), it has the atomic mass (23) (weight when compared to a carbon atom) and the atomic number (11) which is also the number or protons in the nucleus and electrons in its orbit.  To determine the amount of neutrons, subtract the atomic number from the mass number (12) (what is left of the 23 particles in the atom assumed to be neutral).

The Table Continued…  The table is divided into several groups or families.  The most common groups are metals, non-metals, and metalloids.

Properties of Metals  Metals are good conductors of heat and electricity.  Metals are shiny.  Metals are ductile (can be stretched into thin wires).  Metals are malleable (can be pounded into thin sheets).  A chemical property of metal is its reaction with water which results in corrosion.

Properties of Non-Metals  Non-metals are poor conductors of heat and electricity.  Non-metals are not ductile or malleable.  Solid non-metals are brittle and break easily.  They are dull.  Many non-metals are gases. Sulfur

Properties of Metalloids  Metalloids (metal-like) have properties of both metals and non-metals.  They are solids that can be shiny or dull.  They conduct heat and electricity better than non-metals but not as well as metals.  They are ductile and malleable. Silicon

The Bohr-Rutherford Diagram  As mentioned before, these diagrams are used to show the number and specific arrangement of electrons in an element.  In the nucleus, place the element symbol in standard notation. This will easily allow you to determine how many valence electrons the element has.  The amount of electrons in the outer valence determines how reactive an element is (e.g. sodium is very reactive with water)   These are some examples of B-R diagrams. Copy the correct format from the blackboard.

Check Your Understanding  Complete the following questions from your textbook:  #1-4 on page 163.  #1-6 on page 167.  #1-4 on page170  A, B D-F on page 166.