chapter 5 atoms and bonding table of contents chapter preview 5.1 atoms, bonding, and the periodic...

Chapter 5 Atoms and Bonding

Table of ContentsChapter Preview

5.1 Atoms, Bonding, and the Periodic Table

5.2 Ionic Bonds

5.3 Covalent Bonds

5.4 Bonding in Metals


Chapter Preview Questions

1. The atom is made of protons, electrons, and

a. valence electrons.

b. neutrons.

c. molecules.

d. ions.



2. Reactant atoms and molecules interact to form products with

a. identical physical properties.

b. different physical properties.

c. identical chemical properties.

d. different chemical properties.



3. In chemical reactions, the number of atomsa. varies according to the elements involved.b. changes from one reactant to another.c. stays the same.d. depends on atom arrangement.



4. Compounds are formed bya. combining two or more different elements.b. bombarding atoms with high-speed particles.c. combining two or more different nuclei.d. dissolving a solid in a liquid.


Section 1: Atoms, Bonding, and the Periodic Table

Standard 8.3.f: Students know how to use the periodic table to identify elements in simple compounds.


Valence Electrons and BondingHow is the reactivity of elements related to valence electrons in atoms?

Valence electrons

The number of valence electrons in an atom of an element determines the ways in which the atom can bond with other atoms.

•Electrons in the outermost shell of an atom.•Have the highest energy level.•Involved in bonding between atoms.


Valence Electrons and Bonding

Electron Dot Diagrams Include the symbol for an element surrounded by dots that represent the number of valence electrons.


Valence Electrons and BondingChemical Bond

The Rule of 8

•The force of attraction that holds two atoms together as a result of the rearrangement of electrons between them.•Electrons may be transferred from one atom to another, or they may be shared between the atoms.

Atoms are unlikely to react when they have 8 valence electrons.


How the Periodic Table Works

What does the periodic table tell you about the atoms of the elements?

The periodic table reveals the underlying atomic structure of atoms, including the arrangement of the electrons.


How the Periodic Table WorksThe number of valence electrons varies by group.

Group 3 through 12 elements do not follow the same pattern as the other groups!

•Group 1 elements have 1 valence electron.•Group 2 elements have 2 valence electrons.•Groups 3 – 12 have 1 to 2 valence electrons.•Group 13 elements have 3 valence electrons.•Groups 14 – 18 have 4, 5, 6, 7, and 8 valence electrons, respectively.


Example of Group 1 elements

Lithium Atom:

3 Protons/3 Neutrons

3 Electrons – 1 in Valence Shell

Sodium Atom:

11 Protons/11 Neutrons

11 Electrons – 1 in Valence Shell


Section 1 Quick QuizThe electrons involved in bonding between atoms are

A. inside the nucleus.

B. closest to the nucleus.

C. positively charged.

D. valence electrons.

Answer:

D – Valence electrons


Section 1 Quick QuizHow many valence electrons do Group 13 elements have?

A. 5

B. 8

C. 3

D. 6

Answer:

C – 3 Valence Electrons


Section 1 Quick QuizWhat is the greatest number of valence electrons an atom can have?

A. 5

B. 8

C. 3

D. 6

Answer:

B – 8 Valence Electrons


Section 1 Quick QuizWhich Group of elements is the least reactive?

A. Group 1

B. Group 2

C. Group 17

D. Group 18

Answer:

D – Group 18


Section 1 Quick QuizEach family in the periodic table has its own characteristic properties based on the number of

A. valence electrons

B. neutrons

C. protons

D. ions

Answer:

A – Valence electrons


Section 1 Quick QuizIf atoms of a halogen nonmetal (Group 17) gain one electron, the atoms then have

A. no valence electrons.

B. 7 valence electrons.

C. 8 valence electrons.

D. 17 valence electrons.

Answer:

C – 8 valence electrons


Section 2: Ionic Bonds

Standard 8.3.b: Students know that compounds are formed by combining two or more different elements and that compounds have properties that are different from their constituent elements.

Standard 8.3.c: Students know that atoms and molecules form solids by building up repeating patterns, such as the crystal structure of NaCl or long-chain polymers.


IonsWhat is an ion?

How do ions form bonds?

•An ion is an atom or group of atoms that has an electric charge.•When an atom loses an electron it becomes a positive ion.•When an atom gains an electron it becomes a negative ion.

Ionic bonds form as a result of the attraction between positive and negative ions.


Ionic CompoundsSodium has 1 valence electron

Chlorine has 7 valence electrons

http://web.jjay.cuny.edu/~acarpi/NSC/salt.htm


Chemical Formulas and NamesHow are the formulas and names of ionic compounds written?

Positive Negative

Ion + Ion -

NaCl

•When ionic compounds form, the ions come together in a way that balances out the charges on the ions. The chemical formula for the compound reflects this balance.

•For an ionic compound, the name of the positive ion comes first, followed by the name of the negative ion.


Chemical Formulas and NamesWhat is a chemical formula?

What is a subscript?

Chemical

Formula

It is a combination of symbols that shows the ratio of elements in a compound.

A subscript tells you the ratio of elements in the compound.

CO2 Subscript

The ratio of Carbon to Oxygen is 1 to 2.


Properties of Ionic CompoundsWhat are the properties of ionic compounds?

•In general, ionic compounds are hard, brittle solids with high melting points.

•When melted or dissolved in water, they conduct electric current.


Section 2 Quick QuizWhen an atom loses an electron, it becomes a

A. positive ion.

B. negative ion.

C. neutral ion.

D. neutral atom.

Answer:

A – positive ion


Section 2 Quick QuizAn ionic bond is an attraction between

A. similarly charged ions.

B. oppositely charged ions.

C. neutral ions.

D. neutral atoms.

Answer:

B – oppositely charged ions


Section 2 Quick QuizIonic compounds are electrically

A. charged

B. positive

C. neutral

D. negative

Answer:

C – neutral


Section 2 Quick QuizIn what form can an ionic compound conduct electricity?

A. as a solid

B. when dissolved in water

C. as a crystal

D. when warmed slightly

Answer:

B – when dissolved in water


Section 2 Quick QuizWhich of the following is a characteristic property of ionic compounds?

A. They have low melting points.

B. They have low boiling points.

C. They form hard, brittle crystals with characteristic shapes.

D. They contain no charged particles.

Answer:

C – They form hard, brittle crystals with characteristic shapes


Section 2 Quick QuizIn the chemical formula for an ionic compound, which item is written first?

A. positive ion

B. negative ion

C. subscript

D. charge

Answer:

A – positive ion


Section 3: Covalent Bonds

Standard 8.3.b: Students know that compounds are formed by combining two or more different elements and that compounds have properties that are different from their constituent elements.

Standard 8.7.c: Students know substances can be classified by their properties, including their melting temperature, density, hardness, and thermal and electrical conductivity.


How Covalent Bonds Form

What holds covalently bonded atoms together?

The force that holds atoms together in a covalent bond is the attraction of each atom’s nucleus for the shared pair of electrons.



How do double and triple bonds form?

Double and triple bonds can form when atoms share more than one pair of electrons.



A carbon dioxide molecule has two double bonds.



A nitrogen molecule is an example of a triple bond


Molecular Compounds

What are the properties of molecular compounds?

•Molecular compounds generally have lower melting points and boiling points than ionic compounds.•They do not conduct electric current when melted or dissolved in water.


Unequal Sharing of ElectronsHow does unequal sharing of electrons affect molecules?

Polar bond

Nonpolar bond

Unequal sharing of electrons causes the bonded atoms to have slight electrical charges.

A covalent bond in which electrons are shared unequally.

A covalent bond in which electrons are shared equally.


Unequal Sharing of Electrons

Fluorine forms a nonpolar bond with another fluorine atom.



In hydrogen fluoride, fluorine attracts electrons more strongly than hydrogen does, so the bond formed is polar.



A carbon dioxide molecule is a nonpolar molecule because of its straight-line shape.



In contrast, a water molecule is a polar molecule because of its bent shape.


Water Molecule – Polar Bonding

http://web.jjay.cuny.edu/~acarpi/NSC/salt.htm


Section 3 Quick QuizA chemical bond formed when two atoms share electrons is called a(n)

A. ionic bond

B. covalent bond

C. polyatomic bond

D. crystal bond

Answer:

B – covalent bond


Section 3 Quick QuizWhat is a double bond?

A. a bond between two atoms

B. one pair of electrons shared between two atoms

C. two pairs of electrons shared between two atoms

D. two pairs of electrons shared between four atoms

Answer:

C – two pairs of electrons shared between two atoms


Section 3 Quick QuizA covalent bond in which electrons are shared unequally is

A. polar.

B. a double bond.

C. ionic.

D. polyatomic.

Answer:

A – polar


Section 3 Quick QuizWater is polar and oil in nonpolar. What happens when the two liquids are poured into the same container?

A. Both liquids become nonpolar.

B. A gas is produced.

C. The liquids mix well.

D. The liquids do not mix.

Answer:

D – The liquids do not mix


Section 4: Bonding in Metals

Standard 8.7.c: Students know substances can be classified by their properties, including their melting temperature, density, hardness, and thermal and electrical conductivity.


Metals and AlloysHow do the properties of metals and alloys compare?

Alloy

Alloys are generally stronger and less reactive than the pure metals from which they are made.

A mixture of two or more elements, at least one of which is a metal.

Example: Stainless steel – an alloy of iron, carbon, nickel, and chromium.


Metallic BondingHow do metal atoms combine?

What is a metallic bond?

Metal atoms combine in regular patterns in which the valence electrons are free to move from atom to atom.

An attraction between a positive metal ion and the electrons around it


Metallic PropertiesHow does metallic bonding result in useful properties of metals?

malleable

ductile

The “sea of electrons” model of solid metals explains their ability to conduct heat and electricity, the ease with which they can be made to change shape, and their luster.

Able to be rolled into thin sheets or beaten into complex shapes

Able to be bent easily and pulled into thin strands or wires


Section 4 Quick QuizA mixture that is made of two or more elements-one that is a metal-that has the properties of metal is a(n)

A. polymer

B. monomer

C. alloy

D. ceramic

Answer:

C – alloy


Section 4 Quick QuizSteel is an alloy of one or more elements combined with

A. copper

B. gold

C. iron

D. lead

Answer:

C – iron


Section 4 Quick QuizBrass and steel are examples of

A. alloys

B. elements

C. pure metals

D. valence electrons

Answer:

A – alloys


Section 4 Quick QuizWhich of the following terms means that metals can be rolled into thin sheets, as in aluminum foil, or beaten into complex shapes?

A. polar

B. alloy

C. ductile

D. malleable

Answer:

D – malleable


Section 4 Quick QuizWhich of the following terms means that metals can be pulled into thin strands or wires?

A. polar

B. alloy

C. ductile

D. malleable

Answer:

C – ductile

chapter 5 atoms and bonding table of contents chapter preview 5.1 atoms, bonding, and the periodic...

Documents

number of atoms

reactant atoms

bonding valence electrons

bombarding atoms

bonding section

number of valence electrons

rearrangement of electrons

different chemical properties