History of the periodic table of elements The periodic table of elements is an organized table of all chemical elements identified and recognized. Most forms of the table commonly include information such as each element’s atomic number, chemical properties, and electron configuration. Prior to the periodic table, the elements were arranged in groups of three called triads. These triads were created by Johann Dobereiner, a German chemist, in 1829. Dobereiner arranged these elements in groups of three based on patterns he found in the atomic masses of elements. An English chemist named John Newlands also tried to organize the elements. He created the Law of Octaves but it did not prove to be accurate for any elements heavier than calcium (cK-12
…show more content…
These families, shown and labeled in figure 2, include alkali metals, alkaline earth metals, transition metals, non-metals, metalloids, halogen gases, noble gases, lanthanides (or rare earth metals), and actinides (or rare earth metals). The first family includes group 1 on the periodic table. These metals are extremely reactive as they have 1 electron in their outer orbits. Hydrogen is included in this group because it also has 1 electron in its outer orbit and shares the reactive traits of the metals. They all react with water in increasingly violent ways as you move down the group. The next family, alkaline earth metals, is found in the second group on the periodic table. This group shares the name alkaline because, when dissolved in water, they form basic solutions, or solutions with a pH value greater than 7. Transition metals are located in groups 3 - 12. These elements are specifically categorized for having an incomplete d orbital. Non-metals are found in groups 1, 14, 15, 16, 17, and 18. These elements are not metals and are usually not very good conductors. Nonmetals includes the noble and halogen gases on the periodic table. These elements are most likely gases at room temperature, but can be solids, such as sulfur or carbon. Metalloids have the characteristics of something between nonmetals and metals. Metalloids are found in groups 13, 14, 15, and 16. Some of these elements …show more content…
The most common periodic trends include atomic radius, electron affinity, electronegativity, ionization energy, melting point, and metallic character. Some of these trends are related to each other, as they are directly related. For example, as shown in figures 3-5, the trends of electronegativity, ionization energy, and electron affinity are directly related. Atomic radius is equal to a half of the distance between the nuclei of two atoms of the same element. When moving down a group on the periodic table, the atomic radius increases. The atomic radius also increases when moving from right to left in any period. The capability of an atom to gain an electron is called electron affinity. Electronegativity is the measurement of the atom’s ability to form bonds with electrons. As you move down in a group, the electronegativity decreases. Exceptions to this trend include noble gases, lanthanides, and actinides. Electron affinity is different than electronegativity because it quantitatively measures the energy change that occurs when the atom gains an electron. This trend is directly related to electronegativity. Ionization energy usually considered the opposite of electronegativity. “Ionization Energy is the amount of energy required to remove
These families, shown and labeled in figure 2, include alkali metals, alkaline earth metals, transition metals, non-metals, metalloids, halogen gases, noble gases, lanthanides (or rare earth metals), and actinides (or rare earth metals). The first family includes group 1 on the periodic table. These metals are extremely reactive as they have 1 electron in their outer orbits. Hydrogen is included in this group because it also has 1 electron in its outer orbit and shares the reactive traits of the metals. They all react with water in increasingly violent ways as you move down the group. The next family, alkaline earth metals, is found in the second group on the periodic table. This group shares the name alkaline because, when dissolved in water, they form basic solutions, or solutions with a pH value greater than 7. Transition metals are located in groups 3 - 12. These elements are specifically categorized for having an incomplete d orbital. Non-metals are found in groups 1, 14, 15, 16, 17, and 18. These elements are not metals and are usually not very good conductors. Nonmetals includes the noble and halogen gases on the periodic table. These elements are most likely gases at room temperature, but can be solids, such as sulfur or carbon. Metalloids have the characteristics of something between nonmetals and metals. Metalloids are found in groups 13, 14, 15, and 16. Some of these elements …show more content…
The most common periodic trends include atomic radius, electron affinity, electronegativity, ionization energy, melting point, and metallic character. Some of these trends are related to each other, as they are directly related. For example, as shown in figures 3-5, the trends of electronegativity, ionization energy, and electron affinity are directly related. Atomic radius is equal to a half of the distance between the nuclei of two atoms of the same element. When moving down a group on the periodic table, the atomic radius increases. The atomic radius also increases when moving from right to left in any period. The capability of an atom to gain an electron is called electron affinity. Electronegativity is the measurement of the atom’s ability to form bonds with electrons. As you move down in a group, the electronegativity decreases. Exceptions to this trend include noble gases, lanthanides, and actinides. Electron affinity is different than electronegativity because it quantitatively measures the energy change that occurs when the atom gains an electron. This trend is directly related to electronegativity. Ionization energy usually considered the opposite of electronegativity. “Ionization Energy is the amount of energy required to remove