Presentation on theme: "Chapter 8 “Introduction to the PERIODIC TABLE”. 8.1 The Modern Periodic Table Objectives Describe the kinds of information provided by the periodic table."— Presentation transcript:
8.1 The Modern Periodic Table Objectives Describe the kinds of information provided by the periodic table. Explain the structure of the periodic table in terms of the periods and groups Generalize about the properties of metals, nonmetals, and metalloids on the periodic table. Organize data to develop a table of atomic masses.
The Modern Periodic Table Imagine looking for the answer to a homework question in a book with no table of contents! You would have to thumb through the book-page by page. Why is it easier to find information in a book with a table of con tents? Data that have been organized are easier to find, compare, and interpret.
The Modern Periodic Table One kind of table you use often is a calendar. Think of the calendar as a grid made up of horizontal rows and vertical columns. Each column represents a different day of the week. Each day is repeated in every row through the whole month. periodic.This arrangement of the days in the month is periodic. Things that are periodic have a regular, repeating pattern.
The Modern Periodic Table Like the days of the month, the chemical elements can be arranged in a way that shows a repeating, or periodic, pattern. The chemical properties of the elements repeat as the elements increase in atomic number. periodic table.A table that shows these patterns in the elements' properties is called a periodic table.
At that time, chemists had identified about 70 elements. Mendeleev wrote each element's name, atomic mass, and properties on a card. He ordered the cards from lowest to highest atomic mass and pinned them to his laboratory wall. He grouped elements that had similar properties and put these cards in rows along the wall. In 1869, a Russian chemist named Dmitri Mendeleev created the first periodic table of the elements.
Arranging the elements in this way, Mendeleev ran into several problems. So, he left spaces where no element seemed to fit and put question marks in these spaces. Mendeleev predicted the properties of elements that would be discovered to fill in the blank spaces. One element he left space for, gallium, was discovered in 1875.
The Modern Periodic Table After Mendeleev's death, a British physicist named Henry Moseley carried on Mendeleev's work. Moseley arranged the elements in order of increasing atomic number instead of atomic mass. He discovered that the pattern had no irregularities. modern periodic tableThe position of an element in the modern periodic table is related to its atomic number and the arrangement of electrons in its energy levels.
8.2 Metals Objectives Describe common properties of metals. Generalize about the trend in Groups 13 through 16. Classify metals using the periodic table.
Properties of Metals Metals share many of the same properties. luster.Most metals are silvery or gray in color. When polished, they usually have a surface that reflects light, a quality called luster. Luster is one of the properties of metals. Metals also conduct heat and electricity.
Properties of Metals Most metals are hard and have high melting points, but there are many exceptions. For example, pure gold and pure silver are relatively soft, so they are not often used alone in jewelry and coins. A few metals, such as gallium, have melting points that aren't much higher than room temperature. One metal, mercury, is actually a liquid at room temperature.
Properties of Metals One of the most useful properties of metals is malleability. Materials that are malleable can be flattened, bent, and shaped without breaking. Aluminum, for example, can be flattened into foil. Most metals are also ductile. They can be pulled into wire.
Properties of Metals Why do metals share all these properties? Atoms have their electrons arranged in different energy levels. The electrons in the highest energy level are most important, because they determine an element's properties. Although metals have very different total numbers of electrons, most have from one to three electrons in the highest energy level.
Properties of Metals This low number of outer electrons is what gives metals their properties. A metal atom gives up its outer electrons very easily. When many metal atoms are combined, they all share their outer electrons. These electrons move in a "cloud" around the metal atoms. As a result, a metal can change shape without breaking.
Properties of Metals The metal atoms slide past each other.. This behavior makes metals ductile and malleable. And they conduct electricity because the electrons are free to move.
Alkali Metals alkali metals.Group 1 in the periodic table contains six elements known as the alkali metals. The alkali metals are very reactive. They all have just one electron in the highest energy level of their atoms. Because this electron is so easily lost, alkali metals are found in nature only as positively-charged ions. They combine with negatively-charged ions to form salts.
Alkali Metals Table salt is made of sodium ions and ions of the element chlorine. In pure form, all of the alkali metals have similar properties. For example, they are so soft that they can be cut easily with a knife. They have low densities and melt at low temperatures. Cesium, in fact, will melt on a hot day.
Alkaline Earth Metals alkaline earth metalsThe six elements in Group 2 are called the alkaline earth metals. Alkaline earth metals are reactive, but they are not as reactive as the alkali metals. Alkaline earth metal atoms have two electrons in the highest energy level. Like the alkali metals, they occur in nature as ions combined with other elements.
Alkaline Earth Metals Magnesium and calcium are common alkaline earth metals. Calcium compounds make up much of your bones and teeth. These elements are also used to make building materials, such as cement. The shells of sea animals also contain calcium. The compound magnesium hydroxide, also called milk of magnesia, is used to soothe upset stomachs.
Transition Metals transition metalsMost transition metals are shiny. They have high melting points and are good conductors of heat and electricity. Because of the arrangement of their outer electrons, transition metals are much less reactive than the alkali or alkaline earth metals. They can, however, combine with other elements.
Transition Metals Groups of transition metals share similar properties. For example, iron, cobalt, and nickel are the only metals with magnetic properties. Transition metals are often found in ores. Ores are minerals containing relatively large amounts of metal compounds.
Rare-Earth Metals rare-earth metalsThe elements located in the two separate rows at the bottom of the periodic table are the rare-earth metals. The lanthanide series, elements 58-71, follows lanthanum in Period 6. The actinide series, elements 90-103, follows actinium in Period 7.
Rare-Earth Metals Except for element 61, all of the lanthanides occur in nature. Most of the actinides, however, are synthetic, or made in laboratories. All these elements are radioactive. The most common and known element is Uranium. Uranium is used as nuclear fuel when its converted into plutonium, through a nuclear reaction.
8.3 Nonmetals & Metalloids Objectives 1.Identify the groups containing nonmetals and metalloids. 2.Explain why nonmetals have different properties than metals. 3.List the nonmetals essential to life. 4.Communicate in a chart the different properties of metals, nonmetals, and metalloids.
Nonmetals & Metalloids Did you know your life depends on nonmetals? Look to the right of the zigzag line in the periodic table - in Periods 2 and 3, locate carbon, nitrogen, oxygen, sulfur, and phosphorus. These five nonmetals make up much of your body.
Nonmetals & Metalloids Together with hydrogen, they form fats, carbohydrates, proteins, and nucleic acids- the building blocks of living things.
Nonmetals & Metalloids Metalloids also play an important role in daily life. For example, silicon is used to make computer chips. These chips are used in computers, watches, calculators, and even cars.
Properties of Nonmetals and Metalloids Unlike metals, nonmetals do not have luster and are poor conductors of heat and electricity. Solid nonmetals are usually dull and brittle. They are neither malleable nor ductile, Many nonmetals are gases at room temperature.
Properties of Nonmetals and Metalloids Most nonmetals have many electrons in their highest energy levels. They are held tightly by the nucleus and not free to move around. The atoms of many nonmetals tend to accept electrons from other elements. Many form negatively-charged ions.
Properties of Nonmetals and Metalloids Metalloids have properties of both metals and nonmetals. All the metalloids are shiny solids, but they do not have as much luster as the metals. Most conduct heat and electricity, but not as well as metals.
Boron Group The only element in Group 13 that is not a metal is boron. Boron is a brittle, black metalloid. It is used to make boric acid, a mild antiseptic and laundry products.
Boron Group Below Boron in the periodic table is aluminum. Aluminum, metal has many uses because it is light, soft, and easy to cut. It also conducts heat and electricity very well.
Boron Group Aluminum is the most abundant metal in the earth's crust. However, extracting aluminum from bauxite, its major ore, requires great amounts of energy.
Boron Group The other elements in the boron group are the uncommon metals gallium, indium, and thallium.
Carbon Group How is the lead in your pencil like a diamond? Both are made of carbon. Carbon is the only nonmetal in Group 14. It has two common fo rms: graphite and diamond. Graphite makes up much of the "lead" in your pencil.
Carbon Group Carbon is unique because it can form an unlimited number of different compounds. Most of the compounds found in living things contain carbon.
Carbon Group Silicon and germanium are metalloids. The silicon compounds in rocks and soil make up 60 percent of the earth's crust. Tin and lead are both metals. They are both obtained from mining ore. "Tin" cans are steel food containers lined with tin. Lead and its compounds are poisonous.
Nitrogen Group About 80 percent of the air is nitrogen, a nonmetal in Group 15. You breathe in nitrogen molecules with every breath. Pure nitrogen is a gas that does not combine easily with other elements.
Nitrogen Group Nitrogen is one of the elements essential to life. Living things need nitrogen compounds to make proteins. If its temperature is lowered to -210 o C, nitrogen gas becomes a liquid.
Oxygen Group Oxygen, one of the most important elements on the earth, is also the most abundant. It makes up about 20% of air, 60% of the mass of the human body, and 50% of the mass of the earth's crust. Oxygen is also produced by plants during photosynthesis..
Oxygen Group Sulfur is a nonmetal. Major uses of sulfur include making rubber and sulfuric acid. Selenium is a nonmetal that conducts electricity in the presence of sunlight. Because of this property, selenium is used in light meters, solar cells, and photocopiers.
Halogens The elements in Group 17 are called halogens. Halogen means "salt-former.” Most of the food you eat contains a halogen compound. Halogens combine with metals to form salts. Sodium chloride, or table salt, is a halogen compound. Your body needs sodium chloride to conduct nerve impulses.
Halogens Fluorine is the most reactive of all nonmetals. It comes from a mineral called fluorspar. Fluoride toothpaste is made with fluorine. It is also combined with other nonmetals to make the nonstick coatings on pans.
Halogens Chlorine, bromine, iodine, and astatine are the other halogens. Chlorine is a green gas. Bromine is the only nonmetal that is liquid at room temperature.
Nobel Gases Group 18 contains six colorless gases. They are called noble gases, because they don't readily combine with other elements. All the noble gases exist in the earth's atmosphere. Neon and other noble gases can be found in advertising signs.
Nobel Gases Helium is the second lightest gas. Since it is lighter than air, helium is used to fill balloons and blimps.
Hydrogen Hydrogen is set apart from other elements in the periodic table because its properties do not fit any single group. Although its physical properties resemble those of helium, hydrogen reacts easily with other elements. In some chemical reactions hydrogen acts like a metal; in others it acts like a nonmetal.