Today’s special WELCOME BACK! 4th quarter schedule Science news Periodic notes Activity

Atoms and the periodic table PAb: The student will demonstrate an understanding of the structure and properties of atoms.

All great achievements require time. Maya Angelou Fact: Quasars are believed to be stars, but may actually be distant galaxies.

elements Consist of only one type of atom Some exist in nature Some are diatomic molecules Many exist in combination with other atoms-molecules

Periodic table A highly organized chart listing al the known elements arranged in horizontal rows called periods and vertical columns called groups

Atomic symbol An abbreviation for an element derived from the first one or two letters of the elements name

Atomic mass The number associated with an atom that is the same as the number of protons plus neutrons in its nucleus

metals An element that is generally shiny, opaque, malleable, ductile, and a good conductor of electricity and heat

Non-metals An element that is not shiny, opaque, malleable, ductile, and a good conductor of electricity and heat

metalloids One of six elements – boron, silicon, germanium, arsenic, antimony, tellurium- that exhibit both metallic and nonmetallic properties

periods A horizontal row in the periodic table

groups A vertical column in the periodic table A family of elements that exhibit the same chemical behavior

Mendeleev Periodic table IP I IP II IP III

Today’s special HW check; Q & A Lab Lab due next time

Today’s special 20 minutes to finish lab PT song PT Bee next time…be able to recite at least the first ten elements Notes II HW II & Lab due next time

Valence Electrons Why do the elements in a group have similar properties? Elements in a group have similar properties because they have the same number of valence electrons. A valence electron is an electron that is in the highest occupied energy level of an atom.

Valence Electrons Valence electrons determine chemical reactivity. Properties vary across a period because the number of valence electrons increases from left to right.

The Alkali Metals A Unlike most metals, the alkali metal sodium is soft enough to cut with a knife. B When sodium reacts with water, enough energy is released to ignite the hydrogen that is produced.

The Alkaline Earth Metals Chlorophyll molecules in spinach contain magnesium. An oyster shell and a pearl are both made from calcium carbonate. A plaster cast contains the compound calcium sulfate. Oyster shell with pearl Spinach plant Plaster cast

The Boron Family A compound of boron, silicon, and oxygen is used to make glass that does not shatter easily when its temperature changes rapidly. Glass that contains boron is used to make laboratory glassware and cookware that can go directly from the oven to the refrigerator.

The Carbon Family Silicon is the second most abundant element in Earth’s crust. The clay used to produce this pottery contains silicon compounds called silicates.

The Nitrogen Family The numbers on the bags of fertilizer are, from left to right, the relative amounts of nitrogen, phosphorus, and potassium.

The Oxygen Family Sulfur was one of the first elements to be discovered because it is found in large natural deposits.

The Halogens The elements in Group 7A are called halogens. Each halogen has seven valence electrons. At room temperature, chlorine is a gas, bromine is a liquid, and iodine is a solid.

The Noble Gases When electric current passes through noble gases, they emit different colors. Helium emits pink, neon emits orange-red, argon emits lavender, krypton emits white, and xenon emits blue.

Why do elements in a group have similar chemical properties? Assessment Questions Why do elements in a group have similar chemical properties? They have the same number of valence electrons. They have the same ratio of protons to neutrons. Their atomic masses are multiples of the least massive element of the group. They have the same number of total electrons.

Why do elements in a group have similar chemical properties? Assessment Questions Why do elements in a group have similar chemical properties? They have the same number of valence electrons. They have the same ratio of protons to neutrons. Their atomic masses are multiples of the least massive element of the group. They have the same number of total electrons. ANS: A

Assessment Questions Which Group 2A element would you expect to react most readily with water? beryllium (Be) calcium (Ca) barium (Ba) radium (Ra)

Assessment Questions Which Group 2A element would you expect to react most readily with water? beryllium (Be) calcium (Ca) barium (Ba) radium (Ra) ANS: D

Assessment Questions In general, the metallic characteristics of A group elements within a period decreases from left to right. True False

Assessment Questions In general, the metallic characteristics of A group elements within a period decreases from left to right. True False ANS: T