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Name Date Block 1 2 3 4 Text Tuesday presents: THE PERIODIC TABLE OF ELEMENTS By the 1860s, scientists had discovered 63 different elements. A Russian chemist named Dmitri Mendeleyev tried to classify these elements by their properties. He wrote each element s name and properties on a separate card. When he arranged the cards on a table, he noticed patterns in the properties. Mendeleyev began to develop a table that grouped the elements according to their properties. THE PERIODIC TABLE IS BORN Mendeleyev arranged the elements in rows according to their atomic mass. Recall that the atomic mass is the number of protons and neutrons in an atom s nucleus. In order to calculate this, simply add the number of protons and the number of neutrons together! As Mendeleyev arranged the elements according to their atomic masses, he noticed that many elements with similar properties ended up in the same column. The periodic table is a chart that organizes information about the elements. This chart is shown to the left. It includes a key that explains the information in each box. There is a box for each element. The box contains the element s name, chemical symbol, atomic number, and atomic mass. The atomic mass given is a kind of average of the atomic masses of all the atoms of that element. Over time, the periodic table of elements has grown and developed as scientists have contributed new knowledge. PERIODS AND GROUPS When Mendeleyev arranged the elements in order of their atomic masses, some elements did not seem to fit properly. 1. How did Mendeleyev first try to classify elements? 2. How do you find the atomic mass? 3. What did Mendeleyev notice when he started organizing the elements by their atomic mass? 4. What four pieces of evidence does an element box tell you about an element? 5. What two pieces of information does the atomic number tell you? 6. How are elements arranged on the periodic table today?
Today, elements are arranged in order of the atomic number of each element. Remember that the atomic number of an element is the number of protons in the nucleus of each of its atoms. Each horizontal row is called a period. Periods are numbered from left to right across a row. A vertical column in the periodic table is called a group (or family). Groups are numbered from 1 to 18. A group is also called a chemical family because elements in the same group normally have similar properties. 7. What is the difference between a period and a group? 8. Why are groups sometimes called a chemical family? 9. What is a physical property? PHYSICAL PROPERTIES OF METALS, NONMETALS, and METALLOIDS Each element has its own set of properties. Some properties are shared by elements. Other properties are unique to each element. A physical property is a characteristic that can be observed directly or measured without changing the identity of the substance. Elements can be classified into 3 groups based on their physical properties. METALS: More than 75% of the elements in the periodic table are metals. They are located to the left of the dark, staircase that starts in group 13 and ends in group 16. Most metals have a shiny luster, are malleable (can be beaten or rolled into thin sheets), are ductile (can be stretched into wires), are solid at room temperature with the exception of Mercury and are good conductors heat and electricity. NONMETALS: The nonmetals are found to the right of the steplike line. They include all the elements in Groups 17 and 18 and some in Groups 14, 15, and 16. Unlike metals, solid nonmetals do not conduct heat and electricity well. They tend to have a dull appearance, and are often brittle, which means they are easy to break. Most nonmetals are gases or solids are room temperature. Carbon (C), nitrogen (N), oxygen (O), sulfur (S), fluorine (F), helium (He), and neon (Ne) are nonmetals. One nonmetal, bromine (Br) is a liquid at room temperature. METALLOIDS: Metalloids have some characteristics of both metals and nonmetals. They conduct electricity better than nonmetals, but not as well 10. What are 5 physical properties of metals? 11. What are physical properties of nonmetals? 12. Where are metals and nonmetals found on the periodic table? (left or right) 13. Why are metalloids a special group of elements?
as metals. The metalloids are located along the staircase near the right side of the periodic table in Groups 13, 14, 15, and 16. They include boron (B), silicon(si), germanium (Ge), arsenic (As), and antimony (Sb). CHEMICAL PROPERTIES AND CHEMICAL FAMILIES A chemical property is a characteristic of a substance that cannot be observed without changing the identity of the substance. For example, flammability is a substance s ability to catch fire. Hydrogen is an extremely flammable element. An important chemical property of elements is reactivity. Reactivity is the tendency of a substance to undergo chemical changes or reactions and is determined by an atom s valence electrons. Valence electrons are the electrons found on the outermost orbital of the atom. The more reactive an element is, the more likely it is to combine with other elements. The most reactive elements are the alkali metals in Group 1 because they have 1 valence electron. Halogens are nonmetals in Group 17. The halogens are the most reactive nonmetals because they are 1 valence electron away from having a full valence orbital. Halogens react with alkali metals to form salts for example sodium (Na) reacting with chlorine (Cl). ALKALI METAL (Na) HALOGEN (Cl) 14. If an element is found to the RIGHT of the metalloids, what properties do you think it would have? 15. What is a chemical property? 16. What is reactivity and how is it determined? 17. Why are alkali metals the most reactive elements? 18. What do alkali metals and halogens form when they react with one another? Noble gases, Group 18, are the least reactive of all elements because they already have a full valence orbital! At one time, noble gases were considered inert, or unable to react chemically. However in 1962, scientists produced a substance containing xeon (Xe) and fluorine (Fl), and have produced many other substances involving noble gases since then. In nature, however, noble gases rarely react with other elements. 19. Which group is the least reactive? 20. What does inert mean?
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Answer key Name Date Block 1 2 3 4 Text Tuesday presents: THE PERIODIC TABLE OF ELEMENTS By the 1860s, scientists had discovered 63 different elements. A Russian chemist named Dmitri Mendeleyev tried to classify these elements by their properties. He wrote each element s name and properties on a separate card. When he arranged the cards on a table, he noticed patterns in the properties. Mendeleyev began to develop a table that grouped the elements according to their properties. THE PERIODIC TABLE IS BORN Mendeleyev arranged the elements in rows according to their atomic mass. Recall that the atomic mass is the number of protons and neutrons in an atom s nucleus. In order to calculate this, simply add the number of protons and the number of neutrons together! As Mendeleyev arranged the elements according to their atomic masses, he noticed that many elements with similar properties ended up in the same column. The periodic table is a chart that organizes information about the elements. This chart is shown to the left. It includes a key that explains the information in each box. There is a box for each element. The box contains the element s name, chemical symbol, atomic number, and atomic mass. The atomic mass given is a kind of average of the atomic masses of all the atoms of that element. Over time, the periodic table of elements has grown and developed as scientists have contributed new knowledge. PERIODS AND GROUPS When Mendeleyev arranged the elements in order of their 1. How did Mendeleyev first try to classify elements? Medeleyev first classified elements by their properties. 2. How do you find the atomic mass? To calculate the atomic mass, you add the protons + the neutrons. 3. What did Mendeleyev notice when he started organizing the elements by their atomic mass? To calculate the atomic mass, you add the protons + the neutrons. 4. What four pieces of evidence does an element box tell you about an element? An element box tells you the element s name, it s atomic mass, it s atomic number, and it s chemical symbol. 5. What two pieces of information does the atomic number tell you? The atomic number tells you the number of protons and the number of electrons. 6. How are elements arranged on the periodic table today? Elements are arranged their atomic numbers.
atomic masses, some elements did not seem to fit properly. Today, elements are arranged in order of the atomic number of each element. Remember that the atomic number of an element is the number of protons in the nucleus of each of its atoms. Each horizontal row is called a period. Periods are numbered from left to right across a row. A vertical column in the periodic table is called a group (or family). Groups are numbered from 1 to 18. A group is also called a chemical family because elements in the same group normally have similar properties. PHYSICAL PROPERTIES OF METALS, NONMETALS, and METALLOIDS Each element has its own set of properties. Some properties are shared by elements. Other properties are unique to each element. A physical property is a characteristic that can be observed directly or measured without changing the identity of the substance. Elements can be classified into 3 groups based on their physical properties. METALS: More than 75% of the elements in the periodic table are metals. They are located to the left of the dark, staircase that starts in group 13 and ends in group 16. Most metals have a shiny luster, are malleable (can be beaten or rolled into thin sheets), are ductile (can be stretched into wires), are solid at room temperature with the exception of Mercury and are good conductors heat and electricity. NONMETALS: The nonmetals are found to the right of the steplike line. They include all the elements in Groups 17 and 18 and some in Groups 14, 15, and 16. Unlike metals, solid nonmetals do not conduct heat and electricity well. They tend to have a dull appearance, and are often brittle, which means they are easy to break. Most nonmetals are gases or solids are room temperature. Carbon (C), nitrogen (N), oxygen (O), sulfur (S), fluorine (F), helium (He), and neon (Ne) are nonmetals. One nonmetal, bromine (Br) is a liquid at room temperature. METALLOIDS: Metalloids have some characteristics of both metals and nonmetals. They conduct electricity 7. What is the difference between a period and a group? Periods are horizontal rows and groups are vertical columns. 8. Why are groups sometimes called a chemical family? Groups are called chemical families because they have similar properties. 9. What is a physical property? A physical property is a characteristic that can be observed without altering the substance. 10. What are 5 physical properties of metals? 5 properties of metals are that they have a shiny luster, they are malleable, they are ductile, they are solid and they conduct heat + electricity. 11. What are physical properties of nonmetals? Nonmetals do not conduct heat + electricity, they are dull in appearance and they are brittle. 12. Where are metals and nonmetals found on the periodic table? (left or right) Metals are on the LEFT and nonmetals are on the RIGHT. 13. Why are metalloids a special group of elements? They have properties of both metals + nonmetals.
better than nonmetals, but not as well as metals. The metalloids are located along the staircase near the right side of the periodic table in Groups 13, 14, 15, and 16. They include boron (B), silicon(si), germanium (Ge), arsenic (As), and antimony (Sb). CHEMICAL PROPERTIES AND CHEMICAL FAMILIES A chemical property is a characteristic of a substance that cannot be observed without changing the identity of the substance. For example, flammability is a substance s ability to catch fire. Hydrogen is an extremely flammable element. An important chemical property of elements is reactivity. Reactivity is the tendency of a substance to undergo chemical changes or reactions and is determined by an atom s valence electrons. Valence electrons are the electrons found on the outermost orbital of the atom. The more reactive an element is, the more likely it is to combine with other elements. The most reactive elements are the alkali metals in Group 1 because they have 1 valence electron. Halogens are nonmetals in Group 17. The halogens are the most reactive nonmetals because they are 1 valence electron away from having a full valence orbital. Halogens react with alkali metals to form salts for example sodium (Na) reacting with chlorine (Cl). ALKALI METAL (Na) HALOGEN (Cl) Noble gases, Group 18, are the least reactive of all elements because they already have a full valence orbital! At one time, noble gases were considered inert, or unable to react chemically. However in 1962, scientists produced a substance containing xeon (Xe) and fluorine (Fl), and have produced many other substances involving noble gases since then. In nature, however, noble gases rarely react with other elements. 14. If an element is found to the RIGHT of the metalloids, what properties do you think it would have? It would be a nonmetal so it would be brittle, dull and not conduct heat + electricity. 15. What is a chemical property? A chemical property is a characteristic of something that can only be seen after changing the substance 16. What is reactivity and how is it determined? Reactivity is determined by the valence electrons. 17. Why are alkali metals the most reactive elements? Alkali metals are very reactive because they have 1 valence electron. 18. What do alkali metals and halogens form when they react with one another? Alkali metals are very reactive because they have 1 valence electron. 19. Which group is the least reactive? Noble Gases are the least reactive group. 20. What does inert mean? Inert means unable to react chemically.