Chapter Menu Lesson 1: How Atoms Form Compounds Lesson 2: Forming Solids Click on a hyperlink to view the corresponding lesson.

5.1 How Atoms Form Compounds chemical formula molecule chemical bond ionic bond valence covalent bond

5.1 How Atoms Form Compounds What is a compound? A compound is a pure substance that contains two or more elements. Compounds are chemical combinations of elements with properties that are different from the elements that formed them.

Chemical Formulas for Compounds 5.1 How Atoms Form Compounds Chemical Formulas for Compounds A chemical formula contains atomic symbols and subscripts to show the elements and the number of atoms of each element in the compound.

5.1 How Atoms Form Compounds Describing Compounds A water molecule, or H2O, is two hydrogen atoms bonded to one oxygen atom. The subscript number shows how many atoms the element are in the compound. A molecule is a neutral particle that forms as a result of electron sharing. How can a molecule model be built?

Describing Compounds (cont.) 5.1 How Atoms Form Compounds Describing Compounds (cont.) The chemical formula for sucrose, C12H22O11, includes all the atoms in one molecule.

Formulas and the Law of Definite Proportion 5.1 How Atoms Form Compounds Formulas and the Law of Definite Proportion A pure compound will always contain the same elements in the same proportion by mass.

Compounds and Their Elements 5.1 How Atoms Form Compounds Compounds and Their Elements Compounds have different properties than the elements that make them up. Sodium chloride is table salt. Sodium is a soft metal. Chlorine is a greenish-yellow gas.

Ionic Bonds and Ionic Compounds 5.1 How Atoms Form Compounds Ionic Bonds and Ionic Compounds A chemical bond is a force that holds atoms together in a compound. An ionic bond is an electrical attraction between positively and negatively charged ions in an ionic compound.

Ionic Bonds—Transferring Electrons 5.1 How Atoms Form Compounds Ionic Bonds—Transferring Electrons An atom can become charged by transferring one or more electrons to another atom. Both atoms become charged particles, or ions.

Ionic Bonds—Transferring Electrons 5.1 How Atoms Form Compounds Ionic Bonds—Transferring Electrons (cont.) A lithium atom gives up an electron to a fluorine atom. The result is a positively charged lithium ion and a negatively charged fluoride ion.

Ionic Bonds—Transferring Electrons 5.1 How Atoms Form Compounds Ionic Bonds—Transferring Electrons (cont.) The two ions have opposite charges and are attracted to each other. Lithium fluoride is the simplest type of compound, made only of two elements and known as a binary compound.

Ionic Bonds—Transferring Electrons 5.1 How Atoms Form Compounds Ionic Bonds—Transferring Electrons (cont.)

5.1 How Atoms Form Compounds Ionic Compounds Elements in the same column on the periodic table form a group. Metals in Group 1 can transfer 1 electron and will become +1 ions. Non-metals in Group 17 can gain an electron to form −1 ions. When a positive ion from Group 1 and a negative ion from Group 17 combine, a salt like sodium chloride forms.

Other Binary Ionic Compounds 5.1 How Atoms Form Compounds Other Binary Ionic Compounds Group 2 elements are also metals and can lose 2 electrons and form ions with a +2 charge. Elements in Group 16 can gain 2 electrons and form ions with a −2 charge.

Other Binary Ionic Compounds (cont.) 5.1 How Atoms Form Compounds Other Binary Ionic Compounds (cont.) Magnesium can transfer one electron to each of 2 Fluorine atoms to form magnesium fluoride (MgF2).

Properties of Ionic Compounds 5.1 How Atoms Form Compounds Properties of Ionic Compounds Usually solids at room temperature Brittle and break apart easily Have high melting and boiling points Many dissolve in water

Diagramming Electrons— Lewis Dot Diagrams 5.1 How Atoms Form Compounds Diagramming Electrons— Lewis Dot Diagrams A Lewis dot diagram is a system to represent atoms and their electrons. You must know the number of valence electrons an atom has. Valence electrons are the electrons in the outermost energy level.

Diagramming Electrons—Lewis Dot Diagrams 5.1 How Atoms Form Compounds Diagramming Electrons— Lewis Dot Diagrams (cont.) Diagramming Electrons—Lewis Dot Diagrams

5.1 How Atoms Form Compounds Ions and Noble Gases Groups 2–12 of the periodic table are metals and the valence number can vary. Elements in Group 18 are the noble gases. The noble gases are stable because their outer energy levels are filled. Elements that are stable rarely react to form compounds.

Noble Gas Structure by Gaining Electrons 5.1 How Atoms Form Compounds Noble Gas Structure by Gaining Electrons Chlorine can achieve noble gas structure by filling its outer energy levels. Argon is the nearest noble gas to chlorine. Chlorine can become more stable by gaining one electron and forming the chloride ion Cl–.

Noble Gas Structure by Losing Electrons 5.1 How Atoms Form Compounds Noble Gas Structure by Losing Electrons Magnesium can achieve the electron structure of neon, the nearest noble gas on the periodic table. Magnesium can lose two electrons to form the stable ion Mg2+.

Covalent Bonds—Sharing Electrons 5.1 How Atoms Form Compounds Covalent Bonds—Sharing Electrons Ionic bonds form when electrons are transferred. Some elements need to gain or lose too many electrons. A covalent bond is a chemical bond formed when atoms share electrons.

Covalent Bonds—Sharing Electrons 5.1 How Atoms Form Compounds Covalent Bonds—Sharing Electrons (cont.) Carbon has 4 valence electrons. Too much energy is needed for carbon to easily gain or lose 4 electrons.

Covalent Bonds—Sharing Electrons 5.1 How Atoms Form Compounds Covalent Bonds—Sharing Electrons (cont.) Covalent bonds form by sharing electrons. Elements that are close together on the periodic table are more likely to share electrons in a covalent bond than to transfer electrons. Organic compounds are covalent compounds containing carbon atoms and are important for living organisms.

Covalent Bonds—Sharing Electrons 5.1 How Atoms Form Compounds Covalent Bonds—Sharing Electrons (cont.)

Properties of Covalent Compounds 5.1 How Atoms Form Compounds Properties of Covalent Compounds Can be solids, liquids, or gases at room temperature Usually have lower melting and boiling points than ionic compounds Do not usually separate in water Most do not conduct electricity

Single Covalent Bonds Hydrogen has one unpaired electron. 5.1 How Atoms Form Compounds Single Covalent Bonds Hydrogen has one unpaired electron. Two hydrogen atoms share their single electrons to form a pair. The shared pair of electrons is a single covalent bond, which holds the hydrogen molecule H2 together.

Double and Triple Bonds 5.1 How Atoms Form Compounds Double and Triple Bonds Some atoms may form stronger bonds by sharing more than one pair of electrons. A double bond has two pairs of shared electrons and is stronger than a single bond. A triple bond has three pairs of shared electrons and is stronger than a double bond.

5.1 How Atoms Form Compounds B C D Bromine is in Group 17. How many electrons does bromine need to gain or lose to obtain a noble gas structure? A gain one electron B gain two electrons C lose one electron D lose two electrons Lesson 1 Review

Which element can form a negative ion? A carbon B magnesium C chlorine 5.1 How Atoms Form Compounds A B C D Which element can form a negative ion? A carbon B magnesium C chlorine D lithium Lesson 1 Review

What holds two elements together in an ionic bond? 5.1 How Atoms Form Compounds A B C D What holds two elements together in an ionic bond? A covalent bonds from shared electrons B electron clouds combining C unpaired electrons attracting each other D opposite charges on negative and positive ions Lesson 1 Review

End of Lesson 1

5.2 Forming Solids metal metallic bond malleability ductility crystal unit cell polymer monomer

5.2 Forming Solids Metals Metals are elements that are usually shiny, good conductors of electricity and heat, and solid at room temperature.

5.2 Forming Solids Metallic Bonds A metallic bond is formed when many metal atoms share their pooled electrons. Metal atoms can bond to atoms of the same element, or to other metals.

Bonding and Properties 5.2 Forming Solids Bonding and Properties Metals are good conductors because their electrons move freely. Metals can be hammered into sheets or pulled into wires without breaking.

Metal Atoms and Patterns 5.2 Forming Solids Metal Atoms and Patterns Metal atoms combine in a regular pattern in which some electrons are free to move about.

Physical Properties of Metals 5.2 Forming Solids Physical Properties of Metals Malleability is the ability of a metal to be hammered or rolled into sheets. Ductility is the ability of a substance to be pulled into a wire.

5.2 Forming Solids Crystals A crystal is a regular, repeating arrangement of atoms, ions, or molecules. Crystals are formed from repeating patterns. A unit cell is the smallest repeating pattern that shows how atoms, ions, or molecules are arranged in a crystal.

5.2 Forming Solids What is a polymer? A polymer is a covalent compound made up of many repeating units linked together in a chain. A monomer is a single molecule that forms a link in a polymer chain. Many hundreds of monomers link together to form a solid polymer.

5.2 Forming Solids Synthetic Polymers Synthetic polymers, such as polyethylene, are polymers manufactured by humans.

5.2 Forming Solids Natural Polymers All living cells must contain three important kinds of natural organic polymers—proteins, carbohydrates, and nucleic acids.

Natural Polymers (cont.) 5.2 Forming Solids Natural Polymers (cont.) Amino acid monomers join together to form a protein. Protein and carbohydrate polymers shown with their monomers.

What holds carbohydrates together? A ionic bonds B metallic bonds 5.2 Forming Solids A B C D What holds carbohydrates together? A ionic bonds B metallic bonds C covalent bonds D electron clouds Lesson 2 Review

Which of the following is the most malleable? A crystal B polymer 5.2 Forming Solids A B C D Which of the following is the most malleable? A crystal B polymer C metal D monomer Lesson 2 Review

A(n) ____ is the smallest repeating pattern in a crystal. A monomer 5.2 Forming Solids A B C D A(n) ____ is the smallest repeating pattern in a crystal. A monomer B polymer C metallic bond D unit cell Lesson 2 Review

End of Lesson 2

Chapter Resources Menu Chapter Assessment California Standards Practice Concepts in Motion Image Bank Science Online Interactive Table Virtual Lab Click on a hyperlink to view the corresponding feature.

A B C D How many dots are in a Lewis dot diagram for the Group 1 element lithium? A 1 B 2 C 3 D 4 Chapter Assessment 1

Which is an example of a natural polymer? A sodium chloride B C D Which is an example of a natural polymer? A sodium chloride B polyethylene C polysaccharide D quartz Chapter Assessment 2

Why are noble gases unlikely to form compounds with other elements? A They form ionic bonds. B They have 8 valence electrons. C They form covalent bonds. D Their outer energy levels are not filled with electrons. Chapter Assessment 3

Compounds sharing electrons are held together by ____. A ionic bonds B covalent bonds C metallic bonds D polymer chains Chapter Assessment 4

A polymer is made up of many repeating monomers held together by ____. C D A polymer is made up of many repeating monomers held together by ____. A metallic bonds B polymer chains C ionic bonds D covalent bonds Chapter Assessment 5

Which elements are least likely to react with other elements? A metals SCI 3.b A B C D Which elements are least likely to react with other elements? A metals B Group 17 elements C Group 16 elements D Noble gases CA Standards Practice 1

SCI 3.b A B C D In the ionic compound magnesium oxide (MgO), how many electrons did oxygen give magnesium? A 1 B 2 C 3 D none of the above CA Standards Practice 2

Metals are good conductors because ____. A their electrons move freely SCI 3.c A B C D Metals are good conductors because ____. A their electrons move freely B their protons move freely C they have ionic bonds D none of the above CA Standards Practice 3

Noble gases are in which group on the periodic table? A 1 B 2 C 17 SCI 3.f A B C D Noble gases are in which group on the periodic table? A 1 B 2 C 17 D 18 CA Standards Practice 4

Which property of copper allows it to be pulled into wires? SCI 7.c A B C D Which property of copper allows it to be pulled into wires? A ductility B malleability C conductivity D luster CA Standards Practice 5

Concepts in Motion 1

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