61 Organizing the Elements Section Review Answer Key

Affiliate 2. Atoms, Molecules, and Ions

2.5 The Periodic Table

Learning Objectives

By the terminate of this department, yous will be able to:

• State the periodic law and explain the organization of elements in the periodic table
• Predict the general properties of elements based on their location within the periodic table
• Identify metals, nonmetals, and metalloids by their backdrop and/or location on the periodic table

Equally early chemists worked to purify ores and discovered more than elements, they realized that various elements could be grouped together by their like chemic behaviors. 1 such grouping includes lithium (Li), sodium (Na), and potassium (1000): These elements all are shiny, conduct oestrus and electricity well, and accept similar chemical properties. A 2nd group includes calcium (Ca), strontium (Sr), and barium (Ba), which besides are shiny, good conductors of heat and electricity, and take chemical properties in mutual. However, the specific properties of these two groupings are notably different from each other. For case: Li, Na, and 1000 are much more than reactive than are Ca, Sr, and Ba; Li, Na, and Chiliad form compounds with oxygen in a ratio of two of their atoms to one oxygen cantlet, whereas Ca, Sr, and Ba course compounds with one of their atoms to one oxygen atom. Fluorine (F), chlorine (Cl), bromine (Br), and iodine (I) likewise exhibit similar properties to each other, but these properties are drastically unlike from those of whatsoever of the elements higher up.

Dimitri Mendeleev in Russia (1869) and Lothar Meyer in Frg (1870) independently recognized that there was a periodic relationship among the backdrop of the elements known at that time. Both published tables with the elements bundled according to increasing atomic mass. But Mendeleev went one step further than Meyer: He used his table to predict the existence of elements that would have the properties similar to aluminum and silicon, only were yet unknown. The discoveries of gallium (1875) and germanium (1886) provided not bad support for Mendeleev'south work. Although Mendeleev and Meyer had a long dispute over priority, Mendeleev'southward contributions to the development of the periodic table are now more widely recognized (Figure one).

Figure 1. (a) Dimitri Mendeleev is widely credited with creating (b) the first periodic table of the elements. (credit a: modification of work by Serge Lachinov; credit b: modification of work by "Den fjättrade ankan"/Wikimedia Commons)

By the twentieth century, information technology became apparent that the periodic relationship involved atomic numbers rather than diminutive masses. The modern statement of this relationship, the periodic police, is equally follows: the properties of the elements are periodic functions of their atomic numbers. A modern periodic tabular array arranges the elements in increasing order of their diminutive numbers and groups atoms with similar properties in the aforementioned vertical column (Figure 2). Each box represents an element and contains its atomic number, symbol, average atomic mass, and (sometimes) proper name. The elements are arranged in seven horizontal rows, chosen periods or serial, and 18 vertical columns, called groups. Groups are labeled at the top of each column. In the United states, the labels traditionally were numerals with capital letter messages. Still, IUPAC recommends that the numbers 1 through eighteen exist used, and these labels are more common. For the table to fit on a single page, parts of two of the rows, a total of 14 columns, are commonly written below the main body of the tabular array.

Figure 2. Elements in the periodic table are organized co-ordinate to their properties.

Many elements differ dramatically in their chemic and physical properties, but some elements are like in their behaviors. For example, many elements announced shiny, are malleable (able to be deformed without breaking) and ductile (can be drawn into wires), and deport oestrus and electricity well. Other elements are not shiny, malleable, or ductile, and are poor conductors of heat and electricity. We can sort the elements into large classes with common properties: metals (elements that are shiny, malleable, expert conductors of estrus and electricity—shaded yellow); nonmetals (elements that appear dull, poor conductors of estrus and electricity—shaded green); and metalloids (elements that conduct heat and electricity moderately well, and possess some backdrop of metals and some backdrop of nonmetals—shaded regal).

The elements tin can also be classified into the main-grouping elements (or representative elements) in the columns labeled 1, 2, and 13–18; the transition metals in the columns labeled 3–12; and inner transition metals in the ii rows at the bottom of the table (the peak-row elements are chosen lanthanides and the bottom-row elements are actinides; Figure 3). The elements can be subdivided further by more specific properties, such every bit the composition of the compounds they form. For example, the elements in grouping i (the beginning cavalcade) form compounds that consist of 1 atom of the element and 1 atom of hydrogen. These elements (except hydrogen) are known as brine metals, and they all have similar chemic backdrop. The elements in group ii (the second column) form compounds consisting of one atom of the element and two atoms of hydrogen: These are called alkaline earth metals, with similar properties amidst members of that grouping. Other groups with specific names are the pnictogens (group 15), chalcogens (group 16), halogens (group 17), and the noble gases (grouping 18, also known as inert gases). The groups can too exist referred to by the offset element of the group: For example, the chalcogens can be called the oxygen group or oxygen family unit. Hydrogen is a unique, nonmetallic element with backdrop similar to both group 1A and group 7A elements. For that reason, hydrogen may exist shown at the top of both groups, or by itself.

Figure 3. The periodic tabular array organizes elements with similar properties into groups.

Click on this link for an interactive periodic table, which you can utilize to explore the properties of the elements (includes podcasts and videos of each element). Yous may also want to try this one that shows photos of all the elements.

Example 1

Naming Groups of Elements
Atoms of each of the following elements are essential for life. Requite the group name for the following elements:

(a) chlorine

(b) calcium

(c) sodium

(d) sulfur

Solution
The family unit names are as follows:

(a) halogen

(b) alkaline globe metal

(c) alkali metallic

(d) chalcogen

Cheque Your Learning
Give the group proper noun for each of the following elements:

(a) krypton

(b) selenium

(c) barium

(d) lithium

Answer:

(a) noble gas; (b) chalcogen; (c) element of group ii; (d) alkali metal

In studying the periodic table, you might have noticed something about the diminutive masses of some of the elements. Element 43 (technetium), element 61 (promethium), and most of the elements with atomic number 84 (polonium) and college take their atomic mass given in square brackets. This is done for elements that consist entirely of unstable, radioactive isotopes (you will larn more well-nigh radioactivity in the nuclear chemistry affiliate). An boilerplate diminutive weight cannot be determined for these elements because their radioisotopes may vary significantly in relative affluence, depending on the source, or may non even be in nature. The number in foursquare brackets is the atomic mass number (and approximate diminutive mass) of the most stable isotope of that element.

Key Concepts and Summary

The discovery of the periodic recurrence of like backdrop among the elements led to the formulation of the periodic table, in which the elements are arranged in order of increasing atomic number in rows known as periods and columns known equally groups. Elements in the same group of the periodic tabular array have similar chemic properties. Elements tin can be classified as metals, metalloids, and nonmetals, or every bit a main-grouping elements, transition metals, and inner transition metals. Groups are numbered 1–eighteen from left to right. The elements in group i are known as the alkali metals; those in grouping 2 are the alkaline earth metals; those in fifteen are the pnictogens; those in 16 are the chalcogens; those in 17 are the halogens; and those in 18 are the noble gases.

Chemistry End of Chapter Exercises

1. Using the periodic tabular array, allocate each of the post-obit elements as a metal or a nonmetal, then farther classify each equally a main-group (representative) element, transition metal, or inner transition metal:

   (a) uranium

   (b) bromine

   (c) strontium

   (d) neon

   (due east) golden

   (f) americium

   (chiliad) rhodium

   (h) sulfur

   (i) carbon

   (j) potassium

2. Using the periodic table, classify each of the post-obit elements as a metal or a nonmetal, and then farther allocate each as a main-grouping (representative) element, transition metal, or inner transition element:

   (a) cobalt

   (b) europium

   (c) iodine

   (d) indium

   (e) lithium

   (f) oxygen

   (h) cadmium

   (i) terbium

   (j) rhenium

3. Using the periodic table, identify the lightest fellow member of each of the following groups:

   (a) noble gases

   (b) alkaline earth metals

   (c) alkali metals

   (d) chalcogens

4. Using the periodic table, place the heaviest member of each of the following groups:

   (a) alkali metals

   (b) chalcogens

   (c) noble gases

   (d) alkaline earth metals

5. Use the periodic table to give the name and symbol for each of the following elements:

   (a) the noble gas in the aforementioned menstruation as germanium

   (b) the alkali metal earth metal in the same flow as selenium

   (c) the halogen in the same period as lithium

   (d) the chalcogen in the same period as cadmium

6. Use the periodic tabular array to give the name and symbol for each of the following elements:>

   (a) the halogen in the aforementioned menstruation as the alkali metal with 11 protons

   (b) the element of group ii in the same period with the neutral noble gas with 18 electrons

   (c) the element of group 0 in the same row as an isotope with xxx neutrons and 25 protons

   (d) the noble gas in the same period as gold

7. Write a symbol for each of the post-obit neutral isotopes. Include the atomic number and mass number for each.

   (a) the alkali metallic with xi protons and a mass number of 23

   (b) the noble gas chemical element with 75 neutrons in its nucleus and 54 electrons in the neutral cantlet

   (c) the isotope with 33 protons and 40 neutrons in its nucleus

   (d) the alkaline earth metallic with 88 electrons and 138 neutrons

8. Write a symbol for each of the following neutral isotopes. Include the diminutive number and mass number for each.

   (a) the chalcogen with a mass number of 125

   (b) the halogen whose longest-lived isotope is radioactive

   (c) the noble gas, used in lighting, with 10 electrons and 10 neutrons

   (d) the lightest alkali metallic with 3 neutrons

Glossary

actinide

inner transition metallic in the bottom of the bottom 2 rows of the periodic table

brine metallic

element in grouping 1

element of group ii

element in group two

chalcogen

element in grouping 16

group

vertical cavalcade of the periodic table

halogen

chemical element in group 17

inert gas

(also, noble gas) element in group eighteen

inner transition metal

(as well, lanthanide or actinide) element in the bottom two rows; if in the first row, besides called lanthanide, or if in the second row, also called actinide

lanthanide

inner transition metal in the top of the lesser ii rows of the periodic tabular array

main-group element

(also, representative element) element in columns 1, ii, and 12–eighteen

metal

element that is shiny, malleable, expert conductor of heat and electricity

metalloid

element that conducts heat and electricity moderately well, and possesses some properties of metals and some properties of nonmetals

element of group 0

(also, inert gas) element in grouping 18

nonmetal

element that appears dull, poor conductor of heat and electricity

period

(also, series) horizontal row of the periodic table

periodic law

backdrop of the elements are periodic function of their atomic numbers.

periodic table

table of the elements that places elements with like chemical properties close together

pnictogen

chemical element in group 15

representative element

(too, master-group chemical element) element in columns ane, 2, and 12–eighteen

series

(also, period) horizontal row of the menstruum table

transition metal

element in columns 3–11

Solutions

Answers to Chemistry End of Chapter Exercises

1. (a) metal, inner transition element; (b) nonmetal, representative element; (c) metal, representative chemical element; (d) nonmetal, representative element; (e) metal, transition element; (f) metallic, inner transition metallic; (one thousand) metallic, transition metal; (h) nonmetal, representative element; (i) nonmetal, representative element; (j) metal, representative chemical element

3. (a) He; (b) Exist; (c) Li; (d) O

5. (a) krypton, Kr; (b) calcium, Ca; (c) fluorine, F; (d) tellurium, Te

7. (a) [latex]_{11}^{23}\text{Na}[/latex]; (b) [latex]_{54}^{129}\text{Xe}[/latex]; (c) [latex]_{33}^{73}\text{As}[/latex] ; (d) [latex]_{88}^{226}\text{Ra}[/latex];

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Source: https://opentextbc.ca/chemistry/chapter/2-5-the-periodic-table/