Chapter 4 Atoms and Elements.pdf

Chapter 4 Atoms and Elements.pdf - Chapter 4 Atoms and...

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Unformatted text preview: Chapter 4: Atoms and Elements Monday, September 25, 2 017 5:32 PM What is the periodic table and how is the periodic table organized? Why is the periodic table organized the way it is? Identify the location of alkali metals, transition metals, non-­‐metals, metalloids, halogens and inert gases in the periodic table. -­ This chapter explains the periodic table as a table that contains all known elements that are in order of increasing atomic number. This is the "modern periodic table". The first periodic table created by Mendeleev was in order of mass increase form left to right. . The periodic table is arranged in in columns that group similar elements. The contain similar properties that are called groups or families. The left side of the periodic table consists of metals ( good conductors of heat and electricity), the upper right side non-­‐metals (poor conductors of heat and electricity) and elements between the two are metalloids ( intermediate electrical conductivity and can be changed and controlled). Chapter Notes: -­ Atom: smallest identifiable unit of element -­ Element: a substance that cannot be broken down into simplest substances. ○ There are 91 elements in nature and about 91 different kinds of atoms ○ Scientists have found over 20 synthetic elements that are not found in nature 4.2 Indivisible: the atomic theory -­ Atomic theory has three parts: ○ Each element composed of tiny indestructible particles called atoms ○ All atoms of a given element have the same mass and other properties that distinguish them ○ Atoms combine in simple, whole-­‐number ratios to form compounds ALL matter is composed of atoms. 4.5 elements: defined by their numbers of protons Atoms are composed of protons, neutrons, and electrons. It is the number of protons in the nucleus of an atom that identifies it as a particular element. -­ Atoms with 2 protons in their nucleus are helium atoms -­ Atoms with 13 protons in their nucleus are aluminum atoms 4.5 elements: defined by their numbers of protons Atoms are composed of protons, neutrons, and electrons. It is the number of protons in the nucleus of an atom that identifies it as a particular element. -­ Atoms with 2 protons in their nucleus are helium atoms -­ Atoms with 13 protons in their nucleus are aluminum atoms -­ Atoms with 92 protons in their nucleus are uranium atoms -­ This the Atomic Number, which is represented with the symbol Z The periodic table of elements lists all known elements according to their atomic numbers. -­ Each element is represented by a unique chemical symbol, a one-­‐or-­‐two letter abbreviation. -­ The organization of the PT originates from Mendeleev. Put elements in order of increasing relative mass. -­ Modern table, elements are listed in order of increasing atomic number rather than increasing relative mass -­ Metals occupy the left side of the periodic table -­ Good conductors of heat and electricity -­ Produced into flat sheets -­ Drawn into wires -­ Often shiny and tend to lose electrons when they undergo chemical changes -­ Non-­‐metals: Occupy the upper right side of the periodic table -­ Varied properties: solids at room temp, others are gases -­ Poor conductors of heat and electricity -­ Gain electrons when they undergo changes -­ Oxygen, nitrogen, chlorine, iodine -­ Metalloids: semimetals, mixed proteins -­ Intermediate electrical conductivity -­ Can be changed and controlled The elements within a family of main-­‐group elements usually have similar properties and some have a group name. -­ Noble gases: Group 8A. Chemically inert gasses. The most familiar noble gas is helium. -­ Helium is chemically stable meaning it wont combine with other elements to form compounds, also meaning it is safe to put into balloons. -­ Neon, argon, krypton, and xenon are other types of noble gases. -­ Alkali Metals: Group 1A. All very reactive metals. -­ A marble sized piece of sodium can explode when dropped into water. -­ Alkali metals include lithium, potassium, rubidium. -­ Alkali earth metals: Group 2A. Fairly reactive, but not like alkali metals. -­ Calcium, a type of alkali earth metal. Reacts fairly vigorously when dropped into water but does not explode. -­ Magnesium, strontium, barium. -­ A marble sized piece of sodium can explode when dropped into water. -­ Alkali metals include lithium, potassium, rubidium. -­ Alkali earth metals: Group 2A. Fairly reactive, but not like alkali metals. -­ Calcium, a type of alkali earth metal. Reacts fairly vigorously when dropped into water but does not explode. -­ Magnesium, strontium, barium. -­ Halogens: Group 7A. V ery reactive nonmetals. -­ Chlorine, most familiar halogen. It is a yellow-­‐greenish gas with a pungent odor. Because of its reactivity, people often use chlorine as a sterilizing and disinfecting agent. -­ Bromine, iodine, fluorine. ...
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