Transcript Chapter 2
Elements are the Building Blocks of Matter Elements _______________: a substance that contains only one kind of matter and cannot be broken down or separated into simpler substances. ___________________: all elements have a chemical symbol One or two letters, if only one then it is __________, but if two then the first is capitalized and the second is ____. These internationally recognized symbols (IUPAC) create easy communication between scientists of different nations and give a common scientific language. Twenty Common elements Symbol is the first letter in name Symbol is made from two letters in its name Symbol is based on non-English name Hydrogen (____) Magnesium (_____) Sodium (_____) Carbon (____) Calcium (_____) Potassium (____) Nitrogen (_____) Nickel (_____) Iron (____) Oxygen (_____) Zinc (____) Copper (____) Neon (_____) Silver (____) Helium (_____) Gold (_____) Chlorine (_____) Mercury (____) Silicon (_____) Lead (_____) Question to consider… What is the difference between Co and CO? (hint look at the periodic table for help) Dmitri Mendeleev He organized the known elements at the time according to their known __________ and _____________characteristics He recognized that spaces needed to be held for elements that had yet to be _____________ He left gaps in his table and suggested that elements would be found to fill these gaps Mendeleev’s Periodic Table There are a lot of gaps, but look at the horizontal rows (________) and compare to the current periodic table. Current Periodic Table Periodic Table ______________: a chart that organizes all known elements according to their physical and chemical properties Most versions include the element’s name, symbol, atomic number and the atomic mass ________________: equals the number of __________ in the nucleus in each atom and … equals the mass of the protons in the nucleus (measured in atomic mass units, __________) equals the number of electrons in each atom of an element _____________: the average mass of the atoms in an element. It is written as a decimal and is also measured in amu. Atomic mass = # of _______ + # number of _________ OR: Atomic mass = Atomic # + # of neutrons Complete Activity 2-2A: page 49 Elements are grouped on the basis of similar characteristics Three major groups formed are: _________, _________and _______________ Metals Non-metals Metalloids ____________ ____________ ____________ Conducts _________ Conducts _________ ______________ Non-ductile Non-malleable Does not conduct heat Does not conduct electricity Shiny or dull Not ductile Not malleable Poor heat conductor May conduct electricity __________: ability of a substance to be pulled or stretched __________: ability of a substance to be bent or molded into different shapes Task: Using a blank Periodic Table, we are going to color code and identify the following parts of the periodic table Metals Non-metals Metalliods Alkali Metals Alkaline Earth metals Halogens Noble gases Transition Metals _____________: a horizontal row, Number from 1 to 7 _________________________: 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 halogens www.teacher s.tv/video/3518 Website with a variety of activities related to the periodic table www.nclark.net/PeriodicTable Families 1: Alkali Metals __________________(Column 1) Very _____________ and soft React with ________, _________ and other non-metals __________ melting points Reactivity ______________ as you move down the column Family 2: Alkaline Earth Metals Alkaline Earth Metals (column 2) _______ reactive than Alkali Metals ________ in air if heated, produce bright flames and used in __________________ Also reacts with ___________ Reactivity increases as you move down the column Family 17: Halogens Halogens (Column 17) ______________ and __________ reactive Fluorine and Chlorine are______, Bromine is a ______ and Iodine is a ___________ Reactivity ___________as you move down the column Astatine is very rare and little is known about it Family 18: Noble Gases Noble gases (column 18) Most __________ and ________________ At room temperature they are colorless and odorless Some gases, like Argon and Neon are used in light fixtures Helium is ____________ than air and is used in balloons. Why is Hydrogen special? It occupies a unique position because sometimes it acts like a _______ and sometimes it acts like a _______________ Sometimes included with alkali metals or with the halogens or off by itself. Locating Elements on the Periodic Table Make sure you can identify the relative position of elements on the periodic table What element is located at period 2, family 3? __________________ Atomic Structure ___________________ Diagram: shows how many ________________ are in each energy level (electron shell) surrounding the nucleus. __________ 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 __ electrons The next two shells can hold up to a maximum of __ electrons and the fourth shell can hold up to a maximum of __ electrons. Known as the ______________ pattern Drawing Bohr-Rutherford Diagrams Need to be able to draw these diagrams for the first 18 elements These diagrams represent the relative energies of the atom’s electrons and do not show the position of the electrons in the atom Electrons do not follow circular paths about the nucleus The shells should be drawn using horizontal lines NOT CIRCLES. How to Draw Bohr-Rutherford Models Step 1: Draw Nucleus Step 2: Put symbol, number of protons and number of neutrons in the Nucleus Step 3: Use the 2-8-8-18 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 Bohr-Rutherford… ___________________Level: the energy level that is the furthest from the nucleus _____________ Electrons: Electrons that are _______away from the nucleus. They occupy the valence energy level Valence electrons have ________energies associated with them than those closer to the nucleus Website to help describe the Bohr atomic model http://videos.howstuffworks.com/hsw/5787-niels-bohrsatomic-model-video.htm Patterns Observed Using Energy Level Diagrams Elements in the same family have the ______ number of electrons in their valence energy level Period number indicates the number of __________ The ___________energy level structure determines how one element will react with another If the valence level is _______, then it is difficult to react (look at Noble gases) Website to show the similar properties of elements in families http://videos.howstuffworks.com/hsw/5793-periodic-table-familiesvideo.htm