Obj I will be able to classify elements

Obj: I will be able to classify elements by their properties. Meaning ~ you will be able to understand how the periodic table is arranged and use the characteristics of elemental families to group elements. n n n Ready. Reporter>Journals please Responsible- complete the warmup Respectful- Please sit in your assigned seats n Warm-up: Please be ready for notes

Periodic Table of Elements

Chemistry Joke Two atoms walking down the street run into each other. One says to the other, "Are you all right? " "No, I lost an electron!" "Are you sure? " "Yeah, I'm positive!"

chlorine gold helium nitrogen silver oxygen mercury hydrogen sodium niobium neodymium carbon

Review: Elements n n Aristotle’s theory of Air, Water, Fire, and Earth. Scientists have identified 90 naturally occurring elements, and created about 28 others.

Elements n The elements, alone or in combinations, make up our bodies our world, our sun, and in fact, the entire universe.

The most abundant element in the Earth’s crust is oxygen.

Matter n All matter is composed of atoms and groups of atoms bonded together, called molecules. ¡ ¡ ¡ Substances that are made from one type of atom only are called pure substances. Substances that are made from more than one type of atom bonded together are called compounds. Compounds that are combined physically, but not chemically, are called mixtures.

Mendeleev n n n In 1869, Dmitri Ivanovitch Mendeléev created the first accepted version of the periodic table. He grouped elements according to their atomic mass, and as he did, he found that the families had similar chemical properties. Blank spaces were left open to add the new elements he predicted would occur.

Periodic Table n The periodic table organizes the 118 known elements n You can predict the physical and chemical properties of the element. n You can also predict what other elements a particular element will react with chemically.

Classifying Elements ?

Review: Atomic Mass Unit (AMU) n n The unit of measurement for an atom is an AMU. It stands for atomic mass unit. One AMU is equal to the mass of one proton.

Atomic Mass Unit (AMU) There are 6 X 1023 or 600, 000, 000, 000 amus in one gram. n (Remember that electrons are 2000 times smaller than one amu). n

Key to the Periodic Table n Elements are organized on the table according to their atomic number. ¡ The atomic number refers to how many protons an atom of that element has. ¡ Hydrogen has 1 proton, so it’s atomic number is 1. ¡ No two elements have the same atomic number.

What’s in a square? n Different periodic tables can include various bits of information, but usually: ¡ ¡ ¡ atomic number symbol atomic mass number of valence electrons state of matter at room temperature.

Atomic Number n n This refers to how many protons an atom of that element has. No two elements, have the same number of protons. Bohr Model of Hydrogen Atom Wave Model

Atomic Mass n n Atomic Mass refers to the “weight” of the atom. It is derived at by adding the number of protons with the number of This is a helium atom He. Its atomic neutrons. mass is 4 (protons plus neutrons). What is its atomic number?

Atomic Mass and Isotopes n Some atoms have more or less neutrons than protons. These are called isotopes. n An atomic mass number with a decimal is the total of the number of protons plus the average number of neutrons.

Symbols C Cu n Carbon Copper n All elements have their own unique symbol. It can consist of a single capital letter, or a capital letter and one or two lower case letters.

Common Elements and Symbols

Valence Electrons n Valence electrons are the electrons in the outer energy level of an atom. n These are the electrons that are transferred or shared when atoms bond together.

Electron Count: 2+2+6+2= 20

Electrons & the Periodic Table n. Elements are grouped because they have similar properties n. In some groups, the elements all have the same number of valence electrons in their atoms

Electrons & the Periodic Table n. In atoms of elements in Groups 1 & 2, the number of valence electrons matches the group number

Electrons & the Periodic Table n. In atoms of elements in Groups 13 -18, the number of valence electrons is 10 fewer than the group number

Electrons & the Periodic Table n. Atoms of elements in Groups 3 -12, the Transition Metals, do not follow a general rule • In Unit A: Chapter 3 addition, helium atoms only have 2 valence electrons

Grouping the Elements - Group 1 n. Group 1: Alkali Metalsn 1 Valence Electron Unit A: Chapter 3 n. All metals except Hydrogen, the Group 1 elements, are the most reactive.

Grouping the Elements - Group 1 n. Group 1: Alkali Metals n 1 Valence Electron Unit A: Chapter 3 n. This means that the atoms of these elements are not stable and will lend valence electrons to other atoms.

Grouping the Elements - Group 1 n. Group 1: Alkali Metals n 1 Valence Electron n. These elements are never found uncombined in nature. Unit A: Chapter 3

Grouping the Elements - Group 1 n. Alkali Metals n. Compounds formed from Alkali metals have many uses for humans • Na. Cl, or Sodium Chloride, is table salt that is used to season your food • Potassium compounds are found in bananas Unit A: Chapter 3

Grouping the Elements - Group 2 n. Group 2: Alkaline-Earth Metalsn 2 Valence Electrons n. Alkaline- Unit A: Chapter 3 Earth metals are very reactive, but not as reactive as Alkali metals.

Grouping the Elements - Group 2 n. Group 2: Alkaline-Earth Metals- 2 Valence Electrons Unit A: Chapter 3 n. This is because it is harder for their atoms to lose 2 valence electrons than for the Alkali metals to lose 1

Grouping the Elements - Group 2 n. Group 2: Alkaline Earth Metals • Magnesium is mixed with other metals to make rims on cars. • Calcium Unit A: Chapter 3 is an important part of the compound that keeps your bones and teeth healthy.

Grouping the Elements Groups 3 -12 n. Groups 3 -12: Transition Metals n. Groups 3 -12 do not have individual group names. Unit A: Chapter 3

Groups 3 -12 n. Groups Unit A: Chapter 3 3 -12 n. The Transition Metals are less reactive than Groups 1 & 2 because they don’t lose their valence electrons as easily.

Grouping the Elements n. Silver and Gold are Transition Metals. Unit A: Chapter 3

Grouping the Elements n. Transition Metals n. Iron, Cobalt, and Nickel, all Transition Metals, are the only elements known to produce a magnetic field. Unit A: Chapter 3

Group 13: Boron Group n. The most common element from Group 13 is aluminum. Unit A: Chapter 3

Group 14: Carbon Group n. The nonmetal Carbon, in Group 14, is often found uncombined in nature. Unit A: Chapter 3

n. Carbon forms both diamonds and charcoal. n. Carbon Unit A: Chapter 3 also forms a wide variety of compounds such as proteins, fats, and carbohydrates, all necessary for life on earth.

Group 15: Nitrogen Group n. Nitrogen, a gas at room temperature, makes up about 78% of the air you breathe. Unit A: Chapter 3

Group 15 n. Nitrogen from the air is combined with Hydrogen to make fertilizer. n. Fertilizer Unit A: Chapter 3 helps grow the crops that

Group 16 n. Oxygen, in Group 16, makes up about 21% of the air you breathe. n. Oxygen is very reactive, combining with many other elements such as iron and carbon. Unit A: Chapter 3

Group 16 n. Sulfur, another common member of Group 16, is used to make sulfuric acid for car batteries. Unit A: Chapter 3

Group 17 Halogens n. Halogens are the very reactive nonmetals in Group 17. n. They react easily because their atoms only need to gain 1 electron to have a complete set Unit A: Chapter 3

Group 18: Noble Gases n. Noble gases are unreactive nonmetals in Group 18. n. These elements’ atoms have full outermost energy levels, and cannot react with other elements Unit A: Chapter 3

Group 18 Noble Gases n. Noble gases like neon glow when electrically charged. n. Argon in a light bulb keeps the filament from burning out. Unit A: Chapter 3

Let’s Review! - n. How 1 - does the periodic table help you identify the physical properties of elements? Unit A: Chapter 3

Properties of Metals n Physical properties of metal are: ¡ they good conductors of heat and electricity. ¡ Metals are shiny. ¡ Metals are ductile (can be stretched into thin wires). ¡ Metals are malleable (can be pounded into thin sheets). n A chemical property of metal is its reaction with water which results in corrosion.

Properties of Non-Metals n n n Sulfur Non-metals are poor conductors of heat and electricity. Non-metals are not ductile or malleable. Solid non-metals are brittle and break easily. They are dull. Many non-metals are gases.

Properties of Metalloids n n Silicon Metalloids (metal-like) have properties of both metals and non-metals. They are solids that can be shiny or dull. They conduct heat and electricity better than nonmetals but not as well as metals. They are ductile and malleable.

Families n n Columns of elements are called groups or families. Elements in each family have similar but not identical properties. For example, lithium (Li), sodium (Na), potassium (K), and other members of family IA are all soft, white, shiny metals. All elements in a family have the same number of valence electrons.

Hydrogen n n The hydrogen square sits atop Family AI, but it is not a member of that family. Hydrogen is in a class of its own. It’s a gas at room temperature. It has one proton and one electron in its one and only energy level. Hydrogen only needs 2 electrons to fill up its valence shell.

Alkali Metals n n n The alkali family is found in the first column of the periodic table. Atoms of the alkali metals have a single electron in their outermost level, in other words, 1 valence electron. They are shiny, have the consistency of clay, and are easily cut with a knife.

Alkali Metals n n n They are the most reactive metals. They react violently with water. Alkali metals are never found as free elements in nature. They are always bonded with another element.

Families Periods n n Columns of elements are called groups or families. Elements in each family have similar but not identical properties. For example, lithium (Li), sodium (Na), potassium (K), and other members of family IA are all soft, white, shiny metals. All elements in a family have the same number of valence electrons. n n Each horizontal row of elements is called a period. The elements in a period are not alike in properties. In fact, the properties change greatly across even given row. The first element in a period is always an extremely active solid. The last element in a period, is always an inactive gas.

What does it mean to be reactive? n n We will be describing elements according to their reactivity. Elements that are reactive bond easily with other elements to make compounds. Some elements are only found in nature bonded with other elements. What makes an element reactive? ¡ ¡ ¡ An incomplete valence electron level. All atoms (except hydrogen) want to have 8 electrons in their very outermost energy level (This is called the rule of octet. ) Atoms bond until this level is complete. Atoms with few valence electrons lose them during bonding. Atoms with 6, 7, or 8 valence electrons gain electrons during bonding.

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Alkaline Earth Metals n n n They are never found uncombined in nature. They have two valence electrons. Alkaline earth metals include magnesium and calcium, among others.

Transition Metals n n n Transition Elements include those elements in the B families. These are the metals you are probably most familiar: copper, tin, zinc, iron, nickel, gold, and silver. They are good conductors of heat and electricity.

Transition Metals n n The compounds of transition metals are usually brightly colored and are often used to color paints. Transition elements have 1 or 2 valence electrons, which they lose when they form bonds with other atoms. Some transition elements can lose electrons in their next-to-outermost level.

Transition Elements n n Transition elements have properties similar to one another and to other metals, but their properties do not fit in with those of any other family. Many transition metals combine chemically with oxygen to form compounds called oxides.

Boron Family n n The Boron Family is named after the first element in the family. Atoms in this family have 3 valence electrons. This family includes a metalloid (boron), and the rest are metals. This family includes the most abundant metal in the earth’s crust (aluminum).

Carbon Family n n n Atoms of this family have 4 valence electrons. This family includes a non -metal (carbon), metalloids, and metals. The element carbon is called the “basis of life. ” There is an entire branch of chemistry devoted to carbon compounds called organic chemistry.

Nitrogen Family n n The nitrogen family is named after the element that makes up 78% of our atmosphere. This family includes nonmetals, metalloids, and metals. Atoms in the nitrogen family have 5 valence electrons. They tend to share electrons when they bond. Other elements in this family are phosphorus, arsenic, antimony, and bismuth.

Oxygen Family n n n Atoms of this family have 6 valence electrons. Most elements in this family share electrons when forming compounds. Oxygen is the most abundant element in the earth’s crust. It is extremely active and combines with almost all elements.

Halogen Family n n The elements in this family are fluorine, chlorine, bromine, iodine, and astatine. Halogens have 7 valence electrons, which explains why they are the most active nonmetals. They are never found free in nature. n. Halogen atoms only need to gain 1 electron to fill their outermost energy level. n. They react with alkali metals to form salts.

Noble Gases n n n Noble Gases are colorless gases that are extremely unreactive. One important property of the noble gases is their inactivity. They are inactive because their outermost energy level is full. Because they do not readily combine with other elements to form compounds, the noble gases are called inert. The family of noble gases includes helium, neon, argon, krypton, xenon, and radon. All the noble gases are found in small amounts in the earth's atmosphere.

Rare Earth Elements n n The thirty rare earth elements are composed of the lanthanide and actinide series. One element of the lanthanide series and most of the elements in the actinide series are called trans-uranium, which means synthetic or man-made.

Elements, Compounds, Mixtures n n n Sodium is an element. Chlorine is an element. When sodium and chlorine bond they make the compound sodium chloride, commonly known as Compounds have different properties than table salt. the elements that make them up. Table salt has different properties than sodium, an explosive metal, and chlorine, a poisonous gas.

Elements, Compounds, Mixtures n n Hydrogen is an element. Oxygen is an element. When hydrogen and oxygen bond they make the compound water. When salt and water are combined, a mixture is created. Compounds in mixtures retain their individual properties. The ocean is a mixture.

Elements, compounds, and mixtures n n n Mixtures can be separated by physical means. Compounds can only be separated by chemical means. Elements are pure substances. When the subatomic particles of an element are separated from its atom, it no longer retains the properties of that element.