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Chapter 6 The Periodic Table 6.1 Organizing the Elements Searching for an organizing principle Chemists used the properties of elements to sort them into groups Mendeleev's Periodic Table In ___________, a Russian chemist and teacher, Dmitri Mendeleev, published a table of the elements. Later that year, a German chemist, Lothar Meyer, published a nearly identical table. __________________ arranged the elements in his periodic table in order of increasing atomic mass. The Periodic Law In the modern periodic table, elements are arranged in order of increasing atomic ___________________. There are _____________ rows, or periods, in the table. Each period corresponds to a principal energy level. The elements within a ___________________, or group, in the periodic table have similar properties. The pattern of properties within a period repeats as you move from one period to the next. This pattern gives rise to the ______________law. Metals, Nonmetals, and Metalloids Three classes of elements are metals, nonmetals, and ___________________. Across a period, the properties of elements become less metallic and more nonmetallic. Most elements are metals--about _________ percent. 1 ________________ are good conductors of heat and electric current. All metals are solids at room temperature, except for mercury. Many metals are ductile, meaning that they can be drawn into wires. Most metals are _______________, meaning that they can be hammered into thin sheets. Nonmetals These elements are in the upper-right corner of the periodic table. Most nonmetals are ___________ at room temperature. A few are solids, such as sulfur and _____________________. Bromine is a dark-red liquid. __________________ are poor conductors of heat and electric current. ________________ is an exception to this rule. Solid nonmetals tend to be brittle. Metalloids There is a heavy stair-step line that separates the metals from the nonmetals. Most of the elements that border this line are metalloids. A _______________ generally has properties that are similar to those of metals and nonmetals. 6.2 Classifying the Elements Squares in the Periodic Table The periodic table displays the symbols and names of the elements, along with information about the structure of their _____________. The Group 1A elements are called ______________ metals. 2 Group 2A elements are called alkaline ______________ metals. The nonmetals of Group 7A are called _________________. Electron Configurations in Groups Elements can be sorted into noble _____________, representative elements, transition metals, or inner transition metals based on their electron configurations. The Noble Gases The ______________ gases are the elements in Group 8A. These nonmetals are sometimes called the inert gases because they rarely take part in a reaction. The Representative Elements Elements in these groups are often referred to as __________________ elements because they display a wide range of physical and chemical properties. Transition Elements Copper, silver, gold, and _____________ are transition metals. The inner transition metals are characterized by f block. 6.3 Periodic Trends Trends in Atomic Size The _______________ radius is one half of the distance between the nuclei of two atoms of the same elements when the atoms are joined. In general, atomic size increases from top to bottom within a _______________ and decreases from left to right across a period. 3 Refer to figure 6.15 page 171 Ions An _________ is an atom or group of atoms that has a positive or negative charge. An atom is electrically neutral because it has equal numbers of _______________ and electrons. Positive and negative __________ form when electrons are transferred between atoms. Atoms of metals, such as sodium, tend to form ions by losing one or more electrons from their highest occupied. An ion with a positive charge is called a _____________. The charge for a cation is written as a number followed by a __________ sign. An ion with a negative charge is called an ___________. The charge for an anion is written as a number followed by a ___________ sign. Trends in Ionization Energy The energy required to remove an electron from an atom is called ______________ energy. First ionization energy tends to decrease from top to bottom within a group and increase from left to right across a __________________. It is relatively easy to remove one electron from a Group 1A. Refer to figure 6.18 page 174 Trends in Ionic Size During reactions between metals and nonmetals, metal atoms tend to lose electrons and nonmetal atoms tend to gain ________________. 4 Cations are always smaller that the atoms from which they form. Anions are always larger that the atoms from which they form. The radius of a sodium ion (95 pm) is about half the radius of a sodium atom (191 pm). The trend is the opposite for ______________________. The radius of a fluoride ion (133 pm) is more than twice the radius of a fluorine atom (62 pm). Trends in Electronegativity __________________________ is the ability of an atom of an element to attract electrons when the atom is in a compound. Scientists use factors such as _________________ energy to calculate values for electronegativity. In general, electronegativity values decrease from top to bottom within a group. For representative elements, the values tend to increase from left to right across a _______________. Metals at the far left of the periodic table have low values. Nonmetals at the far right (excluding noble gases) have high values. 5