Presentation on theme: "Chapter 3: Elements and the Periodic Table"— Presentation transcript:
1 Chapter 3: Elements and the Periodic Table Section 4: Nonmetals and Metalloids
2 Nonmetal An element that lacks most of the properties of a metal. Most are poor conductors of electricity and heat and are reactive with other elements. Solid nonmetals are dull and brittle.
3 Physical Properties State 10 of 16 are gases at room temperature (O, N)Others are solids (C, I, S)1 is liquid (Br)Solid nonmetals are generally opposite of metalsDull (not shiny)Brittle (not malleable or ductile): break or crumble if hit with hammerLower densitiesPoor conductors of heat and electricity
4 Chemical Properties Reactivity Most are reactive; readily form compoundsFluorine (F) is the most reactive known elementSome, group 18, hardly ever form compoundsElectrons during reactions with other atomsWhen nonmetals and metals react, electrons move from the metal to the nonmetal (NaCl)When nonmetals form compounds with other nonmetals, they share electrons and become bonded together into molecules (CH4)
5 Checkpoint 1What happens to the electrons in the atoms of nonmetals when they form bonds with other atoms?
6 Checkpoint 1What happens to the electrons in the atoms of nonmetals when they form bonds with other atoms?They either gain or share electrons.
7 Families of Nonmetals The Carbon Family The Nitrogen Family The Oxygen FamilyThe Halogen FamilyThe Noble GasesHydrogen
8 The Carbon Family Group 14 Atoms can gain, lose, or share four electrons when reacting with other elementsOnly carbon is a nonmetalCarbon has an important role in the chemistry of life and fossil fuels
9 The Nitrogen Family Group 15 Two nonmetals: nitrogen and phosphorus Usually gain or share three electrons when reacting with other elementsNitrogenMakes up 80% of atmosphereDiatomic molecule: consists of two atomsNitrogen fixation by bacteria that turn it into useful form for plantsPhosphorusMuch more reactive, always found in compounds in natureUsed to make matches
10 The Oxygen Family Group 16 Contains three nonmetals: oxygen, sulfur, and seleniumUsually gain or share two electrons when reacting with other elementsOxygenImportant to lifeDiatomic (oxygen you breathe) O2Sometimes triatomic (ozone) O3Can combine with almost every other element (very reactive)Most abundant in Earth’s crust, second-most abundant in atmosphereSulfurSmells like rotten eggsUsed to make rubber, sulfuric acid
11 Checkpoint 2Which family of elements gains or shares three electrons?
12 Checkpoint 2 Which family of elements gains or shares three electrons? The Nitrogen family.
13 The Halogen Family Group 17 Fluorine (F), Chlorine (Cl) Halogen: salt formingAll but astatine (At) are nonmetalsTypically gain or share one electron when they react with other elementsVery reactive; dangerous in uncombined formFluorine (F) is most reactive, reacts with almost every known substanceUseful in compoundsEx. Fluorine compounds added to water supply to help prevent tooth decay
14 The Noble GasesGroup 18Do not ordinarily form compounds because atoms of noble gases do not usually gain, lose, or share electrons (unreactive)Found in small amounts in Earth’s atmosphereNot discovered until the late 1800s
15 HydrogenSimplest and smallest atom: one proton and one electron (some isotopes of hydrogen also have neutrons)Very different from other elements; not in a family (hydrogen is not an alkali metal, even though it’s in the same column)Makes up more than 90% of the atoms in the universe, but only 1% of the mass of Earth’s crust, oceans, and atmosphereRarely found as a pure element; usually in water molecules
16 The Metalloids Have some characteristics of both metals and nonmetals All are solid at room temperatureBrittle, hard, and somewhat reactiveMost useful property is their varying ability to conduct electricityConductivity depends on temperature, exposure to light, or the presence of small amounts of impuritiesUsed to make semiconductors (substances that can conduct electricity under some conditions but not under other conditions) in computer chips, transistors, and lasers.Most common is silicon (Si), which forms a compound with oxygen to make sand and glass
17 Checkpoint 3Which family of nonmetals is unreactive?
18 Checkpoint 3Which family of nonmetals is unreactive?The noble gases.
19 Post-lesson Quiz Which is not a property of nonmetals? a. shininess b. dullnessc. brittlenessd. poor conductivity
20 Post-lesson Quiz2. Where are nonmetals generally located on the periodic table? a. on the right side b. in the middle c. on the left side d. interspersed throughout
21 Post-lesson Quiz3. Some metalloids can conduct electricity under some conditions, but not others. Because of this, these metalloids are sometimes called… a. pseudo-conductors b. semiconductors c. hemiconductors d. biconductors
22 Post-lesson Quiz4. Which element is the simplest and is not part of a family? a. helium b. lithium c. boron d. hydrogen
23 Post-lesson Quiz5. What happens when nonmetal atoms form bonds with other atoms? a. they lose electrons b. they always gain electrons c. they sometimes gain and sometimes share electrons d. they always share electrons