Organization of the Periodic Table
Atomic Number
Every element has an atomic number. This is the number of protons in its atom. A proton is a positively-charged particle in an atom. For example, the element copper has 29 protons in its atom. If you read the periodic table left to right and row by row, the atomic numbers will increase in order until you get to number 57. This is because elements 58-71 and 90-103 appear in order in the two rows at the bottom of the periodic table, which are called the lanthanides and actinides. This number also tells you the number of electrons in a stable atom.
Symbols
Each element is assigned a symbol. The symbol usually corresponds to the element's name. Symbols are usually two letters. However, some symbols have one or three letters.
Families
Each vertical column on the periodic table is an element family. All of the elements in each family have similar properties. They usually react the same in chemical reactions, and they may even look the same and be used for the same purposes. Each family is numbered and has a name. Most periodic tables show the number;'some will even give the name.
Periods
Each horizontal row is called a period. There are seven periods on the periodic table. The lanthanides and actinides really fit in with the sixth and seventh periods. They have been written at the bottom of the table for convenience. The periods tell us the number of VALENCE electrons that the atom contains In Period one, the atoms have one valence electron in their outer shell. Valence electrons are the electrons contained in the valence shell (the outermost electron level) of an atom and which are likely to participate in a chemical reaction through bonding with other atoms, molecules or ions. Different atoms have differents number of levels and different numbers of electrons in those levels, but the levels can only hold a certain number of electrons. The first level, closest to the nucleus, can only hold two electrons. The second level can hold 8, the third level 18, fourth level 32, fifth level 32 and the remaining electrons will be found in the sixth level. None of the known elements have filled the sixth level. (2 + 8 + 18 + 32 + 32 = 82 and the highest number of electrons in a known element is 110, leaving only 28 for the sixth level.
Atomic Mass
The atomic mass tell the average mass of the element. The mass comes from the protons and the neutrons found in the nucleus of the atom. It is an average, since different isotopes have different numbers of neutrons. To find the number of neutrons in an atom, subtract the atomic number (the number of protons) from the atomic mass (total of protons and neutrons. )
Metals, Nonmetals, and Metalloids
Some periodic tables show a bold line in the shape of steps on the right side of the periodic table. All the elements to the left of that line are metals. You can probably see that most of the elements are metals. Metals are elements that are good conductors of heat and electricity. They have a shiny, metallic luster. Metals can also be pounded into shapes or drawn into wire.
All of the elements to the right of the bold step-shaped line are called nonmetals. Non-metals are poor conductors of heat and electricity. They usually have a dull or earthy luster. When pounded, nonmetals usually shatter or form powders.
The elements that touch the bold step-shaped line are called metalloids. These elements have characteristics of both metals and nonmetals.
Solid, Liquid, or Gas
Some periodic tables even tell us whether an element is a solid, liquid, or gas at room temperature. This is sometimes done by color or by the type of print used. Most elements are solids. There are a few gases. Only mercury and bromine are liquids at room temperature. All elements can be solids, liquids, and gases; it simply depends on the temperature.
Radioactivity
Some elements are radioactive and do not have a stable form. Radioactive means that they naturally give off particles. All the elements with an atomic number of 84 or greater are radioactive. Technetium (43) and promethium (61) also have no stable form. All elements have radioactive forms, and most elements have stable forms. Some periodic tables show whether an element is radioactive or stable.
Natural or Manmade
Most of the elements that we see on the periodic table are natural. This means that they occur somewhere in nature. These are called the natural elements. Synthetic elements are elements that are made by humans in laboratories. Many of the heavier elements are synthetic. It was once thought that neptunium (93) and plutonium (94) were synthetic, but now they have been found in small amounts in nature. All of the elements with an atomic number of 95 or greater are synthetic. Some periodic tables show whether an element is natural or synthetic.
Every element has an atomic number. This is the number of protons in its atom. A proton is a positively-charged particle in an atom. For example, the element copper has 29 protons in its atom. If you read the periodic table left to right and row by row, the atomic numbers will increase in order until you get to number 57. This is because elements 58-71 and 90-103 appear in order in the two rows at the bottom of the periodic table, which are called the lanthanides and actinides. This number also tells you the number of electrons in a stable atom.
Symbols
Each element is assigned a symbol. The symbol usually corresponds to the element's name. Symbols are usually two letters. However, some symbols have one or three letters.
Families
Each vertical column on the periodic table is an element family. All of the elements in each family have similar properties. They usually react the same in chemical reactions, and they may even look the same and be used for the same purposes. Each family is numbered and has a name. Most periodic tables show the number;'some will even give the name.
Periods
Each horizontal row is called a period. There are seven periods on the periodic table. The lanthanides and actinides really fit in with the sixth and seventh periods. They have been written at the bottom of the table for convenience. The periods tell us the number of VALENCE electrons that the atom contains In Period one, the atoms have one valence electron in their outer shell. Valence electrons are the electrons contained in the valence shell (the outermost electron level) of an atom and which are likely to participate in a chemical reaction through bonding with other atoms, molecules or ions. Different atoms have differents number of levels and different numbers of electrons in those levels, but the levels can only hold a certain number of electrons. The first level, closest to the nucleus, can only hold two electrons. The second level can hold 8, the third level 18, fourth level 32, fifth level 32 and the remaining electrons will be found in the sixth level. None of the known elements have filled the sixth level. (2 + 8 + 18 + 32 + 32 = 82 and the highest number of electrons in a known element is 110, leaving only 28 for the sixth level.
Atomic Mass
The atomic mass tell the average mass of the element. The mass comes from the protons and the neutrons found in the nucleus of the atom. It is an average, since different isotopes have different numbers of neutrons. To find the number of neutrons in an atom, subtract the atomic number (the number of protons) from the atomic mass (total of protons and neutrons. )
Metals, Nonmetals, and Metalloids
Some periodic tables show a bold line in the shape of steps on the right side of the periodic table. All the elements to the left of that line are metals. You can probably see that most of the elements are metals. Metals are elements that are good conductors of heat and electricity. They have a shiny, metallic luster. Metals can also be pounded into shapes or drawn into wire.
All of the elements to the right of the bold step-shaped line are called nonmetals. Non-metals are poor conductors of heat and electricity. They usually have a dull or earthy luster. When pounded, nonmetals usually shatter or form powders.
The elements that touch the bold step-shaped line are called metalloids. These elements have characteristics of both metals and nonmetals.
Solid, Liquid, or Gas
Some periodic tables even tell us whether an element is a solid, liquid, or gas at room temperature. This is sometimes done by color or by the type of print used. Most elements are solids. There are a few gases. Only mercury and bromine are liquids at room temperature. All elements can be solids, liquids, and gases; it simply depends on the temperature.
Radioactivity
Some elements are radioactive and do not have a stable form. Radioactive means that they naturally give off particles. All the elements with an atomic number of 84 or greater are radioactive. Technetium (43) and promethium (61) also have no stable form. All elements have radioactive forms, and most elements have stable forms. Some periodic tables show whether an element is radioactive or stable.
Natural or Manmade
Most of the elements that we see on the periodic table are natural. This means that they occur somewhere in nature. These are called the natural elements. Synthetic elements are elements that are made by humans in laboratories. Many of the heavier elements are synthetic. It was once thought that neptunium (93) and plutonium (94) were synthetic, but now they have been found in small amounts in nature. All of the elements with an atomic number of 95 or greater are synthetic. Some periodic tables show whether an element is natural or synthetic.
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