If You Know the Atomic Numberbof an Element and Its Position in the Periodic Table You Can

2.5 The Periodic Table

Learning Objectives

By the end of this department, you lot will exist able to:

• Land the periodic law and explicate the organization of elements in the periodic table
• Predict the general properties of elements based on their location within the periodic table
• Place metals, nonmetals, and metalloids past their properties and/or location on the periodic tabular array

Every bit early chemists worked to purify ores and discovered more elements, they realized that various elements could exist grouped together by their similar chemical behaviors. 1 such group includes lithium (Li), sodium (Na), and potassium (K): These elements all are shiny, conduct heat and electricity well, and have similar chemical properties. A 2d grouping includes calcium (Ca), strontium (Sr), and barium (Ba), which as well are shiny, good conductors of heat and electricity, and have chemical properties in common. Nevertheless, the specific properties of these two groupings are notably different from each other. For example: Li, Na, and K are much more than reactive than are Ca, Sr, and Ba; Li, Na, and K form compounds with oxygen in a ratio of ii of their atoms to one oxygen atom, whereas Ca, Sr, and Ba form compounds with ane of their atoms to 1 oxygen cantlet. Fluorine (F), chlorine (Cl), bromine (Br), and iodine (I) also exhibit like backdrop to each other, simply these backdrop are drastically dissimilar from those of any of the elements above.

Dimitri Mendeleev in Russia (1869) and Lothar Meyer in Germany (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. Just Mendeleev went i step further than Meyer: He used his table to predict the existence of elements that would have the backdrop similar to aluminum and silicon, but were nevertheless unknown. The discoveries of gallium (1875) and germanium (1886) provided great support for Mendeleev's work. Although Mendeleev and Meyer had a long dispute over priority, Mendeleev's contributions to the development of the periodic table are now more than widely recognized (Figure 1).

Figure 1. (a) Dimitri Mendeleev is widely credited with creating (b) the first periodic tabular array 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, it became apparent that the periodic relationship involved atomic numbers rather than diminutive masses. The modern statement of this relationship, the periodic constabulary, is equally follows: the backdrop of the elements are periodic functions of their diminutive numbers. A mod periodic table arranges the elements in increasing social club of their atomic numbers and groups atoms with similar properties in the same vertical column (Figure 2). Each box represents an element and contains its diminutive number, symbol, average atomic mass, and (sometimes) name. The elements are arranged in vii horizontal rows, called periods or series, and 18 vertical columns, chosen groups. Groups are labeled at the pinnacle of each column. In the The states, the labels traditionally were numerals with uppercase letters. Even so, IUPAC recommends that the numbers 1 through 18 be used, and these labels are more common. For the table to fit on a unmarried page, parts of ii of the rows, a total of xiv columns, are commonly written below the main torso of the table.

Figure 2. Elements in the periodic table are organized according to their properties.

Many elements differ dramatically in their chemical and physical properties, only some elements are similar 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 bear heat and electricity well. Other elements are not shiny, malleable, or ductile, and are poor conductors of rut and electricity. We tin sort the elements into large classes with common properties: metals (elements that are shiny, malleable, expert conductors of rut and electricity—shaded yellow); nonmetals (elements that appear boring, poor conductors of heat and electricity—shaded green); and metalloids (elements that conduct rut and electricity moderately well, and possess some properties of metals and some properties of nonmetals—shaded purple).

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

Figure 3. The periodic table organizes elements with like backdrop into groups.

Click on this link for an interactive periodic table, which y'all can use to explore the properties of the elements (includes podcasts and videos of each element). You may as well want to endeavor this one that shows photos of all the elements.

Example ane

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

(a) chlorine

(b) calcium

(c) sodium

(d) sulfur

Solution
The family names are as follows:

(a) element of group vii

(b) element of group ii

(c) alkali metal

(d) chalcogen

Check Your Learning
Give the grouping proper noun for each of the following elements:

(a) krypton

(b) selenium

(c) barium

(d) lithium

Answer:

(a) noble gas; (b) chalcogen; (c) alkaline earth metal; (d) brine metal

In studying the periodic table, you might have noticed something about the atomic masses of some of the elements. Element 43 (technetium), element 61 (promethium), and most of the elements with atomic number 84 (polonium) and higher have their atomic mass given in square brackets. This is done for elements that consist entirely of unstable, radioactive isotopes (you lot will learn more than about radioactive decay in the nuclear chemistry chapter). An average atomic weight cannot be determined for these elements considering their radioisotopes may vary significantly in relative affluence, depending on the source, or may non even exist in nature. The number in foursquare brackets is the diminutive mass number (and gauge diminutive mass) of the most stable isotope of that element.

Key Concepts and Summary

The discovery of the periodic recurrence of like properties among the elements led to the conception of the periodic table, in which the elements are arranged in order of increasing atomic number in rows known every bit periods and columns known as groups. Elements in the same group of the periodic table have like chemical backdrop. Elements tin exist classified equally metals, metalloids, and nonmetals, or as a main-group elements, transition metals, and inner transition metals. Groups are numbered 1–18 from left to right. The elements in group ane are known as the alkali metals; those in group 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, classify each of the following elements as a metal or a nonmetal, and so further classify each equally a main-group (representative) element, transition metal, or inner transition metallic:

   (a) uranium

   (b) bromine

   (c) strontium

   (d) neon

   (e) gilt

   (f) americium

   (g) 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 and so farther allocate each as a principal-group (representative) element, transition metal, or inner transition element:

   (a) cobalt

   (b) europium

   (c) iodine

   (d) indium

   (eastward) lithium

   (f) oxygen

   (h) cadmium

   (i) terbium

   (j) rhenium

3. Using the periodic tabular array, identify the lightest member of each of the following groups:

   (a) noble gases

   (b) alkali metal earth metals

   (c) alkali metals

   (d) chalcogens

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

   (a) alkali metals

   (b) chalcogens

   (c) noble gases

   (d) alkali metal earth metals

5. Utilise the periodic table to give the name and symbol for each of the post-obit elements:

   (a) the element of group 0 in the same catamenia every bit germanium

   (b) the element of group ii in the same period as selenium

   (c) the halogen in the same period as lithium

   (d) the chalcogen in the aforementioned period as cadmium

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

   (a) the halogen in the same period every bit the alkaline metal with 11 protons

   (b) the element of group i globe metal in the same menses with the neutral noble gas with 18 electrons

   (c) the noble gas in the same row as an isotope with thirty neutrons and 25 protons

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

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

   (a) the alkali metal with 11 protons and a mass number of 23

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

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

   (d) the element of group ii with 88 electrons and 138 neutrons

8. Write a symbol for each of the following neutral isotopes. Include the atomic 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 brine metallic with 3 neutrons

Glossary

actinide

inner transition metal in the bottom of the bottom two rows of the periodic table

alkaline

element in group 1

alkaline earth metallic

element in group two

chalcogen

element in grouping 16

group

vertical column of the periodic table

halogen

element in group 17

inert gas

(also, element of group 0) element in grouping eighteen

inner transition metal

(also, lanthanide or actinide) element in the lesser two rows; if in the start row, also called lanthanide, or if in the second row, besides chosen actinide

lanthanide

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

main-group element

(also, representative element) element in columns 1, 2, and 12–18

metallic

chemical element that is shiny, malleable, skillful conductor of oestrus and electricity

metalloid

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

noble gas

(likewise, inert gas) element in group 18

nonmetal

element that appears dull, poor conductor of heat and electricity

menstruum

(also, serial) horizontal row of the periodic table

periodic constabulary

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

periodic table

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

pnictogen

element in group fifteen

representative element

(too, primary-group element) element in columns i, ii, and 12–18

series

(as well, period) horizontal row of the menstruum table

transition element

element in columns 3–eleven

Solutions

Answers to Chemistry Finish of Chapter Exercises

ane. (a) metal, inner transition metal; (b) nonmetal, representative element; (c) metallic, representative element; (d) nonmetal, representative element; (e) metal, transition metal; (f) metal, inner transition metal; (g) metallic, transition metal; (h) nonmetal, representative element; (i) nonmetal, representative element; (j) metallic, representative 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{Equally}[/latex] ; (d) [latex]_{88}^{226}\text{Ra}[/latex];

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Source: https://iu.pressbooks.pub/openstaxchemistry/chapter/2-5-the-periodic-table/

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