Presentation on theme: "Elements are the Building Blocks of Matter"— Presentation transcript:
1 Elements are the Building Blocks of Matter Chapter 2Elements are the Building Blocks of Matter
2 ElementsElement: a substance that contains only one kind of matter and cannot be broken down or separated into simpler substances.Chemical Symbol: all elements have a chemical symbolOne or two letters, if only one then it is capitalized, but if two then the first is capitalized and the second is not.These internationally recognized symbols (IUPAC) create easy communication between scientists of different nations and give a common scientific language.
3 Twenty Common elements Symbol is the first letter in nameSymbol is made from two letters in its nameSymbol is based on non-English nameHydrogen (H)Magnesium (Mg)Sodium (Na)Carbon (C)Calcium (Ca)Potassium (K)Nitrogen (N)Nickel (Ni)Iron (Fe)Oxygen (O)Zinc (Zn)Copper (Cu)Neon (Ne)Silver (Ag)Helium (He)Gold (Au)Chlorine (Cl)Mercury (Hg)Silicon (Si)Lead (Pb)
4 Question to consider…What is the difference between Co and CO? (hint look at the periodic table for help)
5 Dmitri MendeleevHe organized the known elements at the time according to their known chemical and physical characteristicsHe recognized that spaces needed to be held for elements that had yet to be discoveredHe left gaps in his table and suggested that elements would be found to fill these gaps
6 Mendeleev’s Periodic Table There are a lot of gaps, but look at the horizontal rows (periods)and compare to the current periodic table.
8 Periodic TablePeriodic table: a chart that organizes all known elements according to their physical and chemical propertiesMost versions include the element’s name, symbol, atomic number and the atomic massAtomic Number: equals the number of protons in the nucleus in each atom and …equals the mass of the protons in the nucleus (measured in atomic mass units, amu)equals the number of electrons in each atom of an element
9 Complete Activity 2-2A: page 49 Atomic mass: the average mass of the atoms in an element. It is written as a decimal and is also measured in amu.Atomic mass = # of protons + # number of neutronsOR: Atomic mass = Atomic # + # of neutronsComplete Activity 2-2A: page 49
10 Elements are grouped on the basis of similar characteristics Three major groups formed are: Metals, non-metals and MetalloidsDuctile: ability of a substance to be pulled or stretchedMalleable: ability of a substance to be bent or molded into different shapesMetalsNon-metalsMetalloidsShinyDuctileMalleableConducts heatConducts ElectricityDullNon-ductileNon-malleableDoes not conduct heatDoes not conduct electricityShiny or dullNot ductileNot malleablePoor heat conductorMay conduct electricity
11 Task:Using a blank Periodic Table, we are going to color code and identify the following parts of the periodic tableMetalsNon-metalsMetalliodsAlkali MetalsAlkaline Earth metalsHalogensNoble gasesTransition Metals
12 Period: a horizontal row, Number from 1 to 7 Chemical Family or group: a vertical column. The elements in a family or group have similar chemical and physical characteristics. They are numbers 1 to 18.Website that demonstrates properties and trends of alkali metals and halogenss.tv/video/3518Website with a variety of activities related to the periodic table
13 Families 1: Alkali Metals Alkali Metals (Column 1)Very reactive and softReact with water, oxygen and other non-metalsLow melting pointsReactivity increases as you move down the column
14 Family 2: Alkaline Earth Metals Alkaline Earth Metals (column 2)Less reactive than Alkali MetalsBurn in air if heated, produce bright flames and used in fireworksAlso reacts with waterReactivity increases as you move down the column
15 Family 17: Halogens Halogens (Column 17) Non-metals and highly reactiveFluorine and Chlorine are gases, Bromine is a liquid and Iodine is a solidReactivity decreases as you move down the columnAstatine is very rare and little is known about it
16 Family 18: Noble Gases Noble gases (column 18) Most stable and unreactiveAt room temperature they are colorless and odorlessSome gases, like Argon and Neon are used in light fixturesHelium is lighter than air and is used in balloons.
17 Why is Hydrogen special? It occupies a unique position because sometimes it acts like a metal and sometimes it acts like a non-metalSometimes included with alkali metals or with the halogens or off by itself.
18 Locating Elements on the Periodic Table Make sure you can identify the relative position of elements on the periodic tableWhat element is located at period 2, family 3?Boron
19 Atomic StructureBohr-Rutherford Diagram: shows how many electrons are in each energy level (electron shell) surrounding the nucleus.Energy Level (or electron shell): the space around the nucleus in which electrons may be found.Shell closest to the nucleus can hold up to a maximum of 2 electronsThe next two shells can hold up to a maximum of 8 electrons and the fourth shell can hold up to a maximum of 18 electrons.Known as the pattern
20 Drawing Bohr-Rutherford Diagrams Need to be able to draw these diagrams for the first 18 elementsThese diagrams represent the relative energies of the atom’s electrons and do not show the position of the electrons in the atomElectrons do not follow circular paths about the nucleusThe shells should be drawn using horizontal lines NOT CIRCLES.
21 How to Draw Bohr-Rutherford Models Step 1: Draw NucleusStep 2: Put symbol, number of protons and number of neutrons in the NucleusStep 3: Use the pattern to fill the energy levels. NOTE: the first energy level is filled first completely before going to the second, the second is filled before going to the third and so on.See page 62, figure 2.24
23 Bohr-Rutherford…Valence Energy Level: the energy level that is the furthest from the nucleusValence Electrons: Electrons that are furthest away from the nucleus. They occupy the valence energy levelValence electrons have higher energies associated with them than those closer to the nucleusWebsite to help describe the Bohr atomic model
24 Patterns Observed Using Energy Level Diagrams Elements in the same family have the same number of electrons in their valence energy levelPeriod number indicates the number of energy levelsThe valence energy level structure determines how one element will react with anotherIf the valence level is full, then it is difficult to react (look at Noble gases)Website to show the similar properties of elements in families