Section 2.2 Periodic Table of the Elements Learning Objectives Know what the periodic table is and how the work of Demitri Mendeleev contributed to its development. Know the difference between atomic number and atomic mass. Be able to determine the number of protons, electrons, and neutrons in an atom for any element. What is the Periodic Table? Periodic Table: a chart that organizes all of the elements based on their properties What is the Periodic Table? Even though there are only about 100 naturally occurring elements, the atoms of these elements make up the millions of substances in all matter! Fluorite = CaF 2 Ca = Calcium + F = Fluorine Sulfuric Acid = H 2 SO 4 H = Hydrogen + S = Sulfur + O = Oxygen What is the Periodic Table? The periodic table contains information about the different elements that make up all the solids, liquids, and gases in the known universe. What is the periodic table? In the 1800s, chemists were aware of many different elements. What is the periodic table? However despite the efforts of many scientists, they had no effective way to organize them! Worksheet #8 - Organizing Elements Organize the images into a grid based on things they have in common. (like colour, shape, etc.). Leave spaces in the grid to predict any missing images. Record your organization system including predicted images on Worksheet #8 Mendeleev and the Periodic Table The elements remained disorganized until the 1860s when a chemist named Demitri Mendeleev developed the periodic table that is still in use today. Mendeleevs Two Major Contributions 1. He arranged the known elements based on their physical and chemical properties. His result was the table shown in the image below: Mendeleevs Two Major Contributions 2. He left empty spaces in his periodic table and predicted new elements would be found to fill these spaces. Mendeleevs Two Major Contributions As he put his table together, he noticed that there seemed to be some elements missing! Mendeleevs Two Major Contributions This was very important because it gave chemists elements to look for and led to the discovery of new elements. Meet the Elements." Using the periodic Table Read Page 49 What is the Periodic Table? Each box on the periodic table contains information about one particular element. It tells us important information about the atoms of that element. Example: Iron Atomic Number Equals the number of protons (p+) in an atom of this element Equals the number of electrons (e-) in an atom of this element **Atoms must have a net neutral charge. This means the # of protons (+) must equal the # of electrons (-)! Mass Number: the rounded atomic mass. It tells you combined number of protons and neutrons. Ex: Iron has a mass number of 56 because atomic mass of 55.8 rounds up! greater than or equal to 0.5 rounds up! (23.5 24) less than 0.5 rounds down! (23.4 23) Summary # of protons = atomic number # of electrons = atomic number (same as protons for an atom!) # of neutrons = mass number atomic number (see example below) Neutrons Example (Iron) Step 1: Find the mass number by rounding the atomic mass: Irons atomic mass is 55.8 so the mass number is 56! Step 2: Subtract the atomic number from the mass number. This gives you the number of neutrons: (on board) Complete Examples on Board Example 2: Sulfur Example 3: Only told that the atomic # is 12 Example 4: Given then # of e - (37) and # of n 0 (49) Complete Worksheet #9 Using the Periodic Table Recap: Element Symbol Atomic # Atomic Mass Mass # # p + # e - # n 0 Br Lesson Objectives: Be able to locate and list the properties of elements belonging to the following groups on the periodic table: (i) metals(ii) non-metals (iii) metalloids (iv) transition metals. Know what periods and families are on the periodic table Be able to identify and list the properties of the following chemical families: (i) alkali metals(ii) alkaline earth metals (iii) halogens(iv) noble gases Recap: The Periodic Table arranges the known elements so that they are grouped together based on their characteristics (or properties). (Not in notes) Sodium and Potassium share many of the same properties. (Not in notes) If scientists discovered new element that reacts with water, they might try to place it near these elements! YAY! Time to get your very own periodic table!!! No, not that type of table Correct Text Book Mistake Page 50 He, B, C, N, O, F are NON-METALS Types of Elements and their Properties Text Section 2.2, p Notes pages Types of Elements Mendeleev identified three main types of elements on the periodic table: 1. Metals 2. Non-Metals 3. Metalloids The image below shows where to identify each type of element on the periodic table. You will need to remember this! Properties of Metals, Non-Metals and Metalloids These three types of elements are identifiable by their different properties MetalsMetalloidsNon-metals Properties of Metals, Non-Metals and Metalloids Know what Ductile and Malleable mean! Examples of ductile and malleable elements..? *Using page 51, summarize the properties of metals and non-metals in the table provided in your notes. Also give three examples of each! OR Element properties: Metals (i) All solid except for Mercury (liquid)Mercury (ii) Shiny (iii) Malleable (iv) Ductile (v) Conduct electricity (vi) Conduct heat Element properties: Non-Metals (i) Solids, liquids and gases (ii) Not shiny (dull) (iii) Non-malleable (brittle) (iv) Not ductile (v) Poor conductors of electricity (vi) Poor conductors of heat Carbon Phosphorous Chlorine What about metalloids? Metalloids: (below table) elements found along the staircase. They have some properties of metals and some properties of non-metals. Boron Tellurium Sample Metalloid Silicon Not all metalloids have the same properties. Some are more like metals, others are more like non-metals. All solids Shiny Brittle (like non-metal) Not ductile May conduct electricity Poor heat conductors Worksheet #10 Complete questions 1-4 on Worksheet #10. Grouping the Elements: Periods and Families Page 11 of your Notes!! Recall that Mendeleev organized the elements based on their properties, with elements that were similar being closer together on the periodic table. As he organized them he noticed patterns in their properties. These patterns helped him structure the periodic table into Periods and Families (also called groups) Grouping the Elements: Periods and Families (Page 11 in notes) Periods: horizontal rows on the periodic table. They are numbered 1 to 7. Grouping the Elements: Periods and Families (Page 11 in notes) Families: Also called groups. They are groups of elements arranged in vertical columns numbered 1 to18. Elements in the same group share similar properties. Families Important Chemical Families You must be able to identify each of these families on the periodic table. You must be familiar with the properties described in your notes for each family. Alkali Metals (Group 1) Properties React strongly with both oxygen and water. Very soft metals (cut with knife) Low melting points for metals (below 200 o C) Reactivity increases down the family (K is more reactive than Na) Examples: Sodium (Na) and potassium (K) (Video) Alkaline Earth Metals (Group 2) Properties Less reactive than Alkali Metals Produce bright coloured flames when burned in air. (Used in fireworks!) Transition Metals (Groups 3-12) Not technically a chemical family because they are spread out over several groups. Found in the centre of the periodic table Grouped together because they all have complex arrangements of electrons which allows them to react in special ways. Some similarities exist in each column (Ex: copper, silver, and gold all resist corrosion.) Common Properties of Element Families Halogens (Column 17) Properties Highly reactive non-metals Contains each room temp: Gases: F and Cl Liquid: Br Solid: I Other Facts Reactivity increases going UP the family! Common Properties of Element Families Noble Gases (Column 18) Properties Most stable elements (means they do not react) All are naturally colourless and odourless gases They glow different colours when electricity is passed through them! Complete Questions 5 and 6 on Worksheet #10 When finished start Homework Questions for portfolio: Page 59 #s 2, 3, 5, 8, 10 12, 17-22, 25 Discussion What do you notice about the Atomic # and Atomic Mass as you go across a period? What do you notice about Atomic # and Atomic Mass as you move down a Family? So what pattern or patterns do we see for the SIZE (mass) of atoms as they are organized on the periodic table?