Science 10: Chemistry

Name: ______________________________

Text: Chapters 4-7

Biology Learning Outcomes

C1. Differentiate between atoms, ions and molecules using knowledge of their structure and components.

C2. Classify substances as acids, bases or salts based on their characteristics, name and formula.

C3. Distinguish between organic and inorganic compounds.

C4. Analyze chemical reactions, including reference to conservation of mass and rate of reaction.

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C5. Explain radioactivity using modern atomic theory.

Science 10: 4.1 Atomic Theory and Bonding

Text: Chapter 4, pages 168-183

Part A: The Atomic Theory

-Subatomic particles make-up atoms, which in turn combine to form elements and compounds.

-

The

table below outlines the various subatomic particles that make up an atom.

-Where does most of an atom’s mass exist? Nucleus, as p and n.

-What makes up most of an atom’s volume? Electron cloud.

-What makes neutral atoms different from electrically charged atoms (ions)?

-Equal number of electrons and protons.

-Differentiate between an element and compound.

-Element: Made up of only one type of atom. (Gold)

-Compound: Made up of two or more different atoms. (Salt)

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Part B: The Nucleus

-What determines the electrical charge of an atom’s nucleus?

-Number of protons.

-Also called the Atomic Number.

-In a neutral atom, what can the Atomic Number also reveal about the atom’s subatomic particles?

-Neutral means no charge, so p = e

-Do like charges (+ and + or – and -) attract? If no, then how an atom’s nucleus held together?

-n act as buffers between the p.

-Examine a periodic table. What is the nuclear charge of Oxygen?

8, so it has 8 protons

Part C: Organization of the Periodic Table

-The periodic table of elements is organized in several ways. What can you observe?

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a) Atomic Number: Elements are listed by their number of protons from left to right.

b) Element Type: There are three types of elements in the periodic table.

i) Metals: On the left

ii) Non-metals: On the right

iii) Metalloids: Staircase on the right

c) Periods: Horizontal row.

d) Group/Family: Vertical column. Elements with the same chemical properties and bond with other elements in similar ways.

i) Group 1: Alkali Metals. Highly reactive metals. (Sodium)

ii) Group 2: Alkaline Earth Metals. Somewhat reactive metals. (Calcium)

iii) Group 3: Halogens. Very reactive non-metals. (Chlorine)

iv) Group 4: Noble Gases. Unreactive gaseous non-metals. (Helium)

e) Transitional Metals: Elements from group 3 through 12.

Part D: Periodic Table and Ion Formation

-Examine the Aluminum atom right. What happens to its electrical charge when 3 e are lost?

-Neutral to a 3+ charge (more p than e).

-Ions are atoms that have lost or gained e to become electrically charged.

-Cations are metal atoms that have lost e to become positively charged. (Remember, Cats have Paws!)

-Multi-valent metals can form ions by losing more than one combination of e (see Iron right). Examine the periodic table and identify some multi-valent metals.

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-Anions are non-metals that gain e. How would this affect their electrical charge?

-More negative as e outnumber p.

-Most non-metals gain e.

-Examine the diagram below. Identify the metal and non-metal.

Part E: Bohr Diagrams

-The arrangement of e in an atom determines how elements behave during chemical change and what compounds are likely to be produced.

-Bohr Diagrams reveal how many electrons are in each shell surrounding the atom’s nucleus.

-Examine the Bohr Diagrams below. What do you notice about the e arrangement?

-

1st Shell: 2 e

2 nd Shell: 8 e

3 rd Shell: 8 e

4 th Shell: 1 in this diagram, but can hold more.

-Valence e: e in the outermost shell. Involved in chemical bonding.

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-Think about the shells as being 3-D spheres and not 2-D circles.

-Remember:

a) The # of p = Atomic #

b) # of n = Mass # - Atomic #

-Draw Bohr Models for an Aluminum atom and ion using the information in the table below.

Part F: Patterns of Electron Arrangement in Periods

-Examine the image right. What type of patterns do you notice in the arrangements of elements on the periodic table and the Bohr models?

-Period # = # of Shells

-Last digit of the group number indicates e # in valence shell (Except for transitional elements and He)

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-As you move left to right across a period the e # increase by one for each element.

-The arrangement of 8 e in the outermost shell is called the Stable Octet. An element with this arrangement does not easily engage in chemical reactions (Noble gases).

Part G: Forming Compounds

-The valence e of two atoms can interact if they are close enough together to produce a compound if the new arrangement is stable.

-Stable chemical bonds have lower energy states (interacting atoms have the same arrangement of valence e).

-What are three ways that e can interact?

a) Lost: Metals lose e to form cations. (Ionic Bond)

b) Gained: Non-metals gain e to form anions. (Ionic Bond)

c) Shared: (Covalent Bond)

1. Ionic Bonding

-Examine the diagram below. How does an ionic bond form?

-Transfer of e from a positive ion (metal) to a negative ion (non-metal).

-Does the NaCl compound have a stable chemical bond?

-Yes, stable octet.

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2. Covalent Bonding

-Examine the diagram right. How does a covalent bond form?

-Sharing of e between non-metals when atoms overlap.

-Valence e are divided into:

a) Bonding Pair: Involved in the covalent bond.

b) Lone Pair: Not used in bonding.

-Differentiate between a covalent compound and a covalent molecule.

-Compound is two non-metallic atoms sharing e; Molecule is a group of atoms sharing one or more pairs of e.

-In the diagrams below label the bonding pair and lone pair and distinguish between covalent compounds and covalent molecules.

Part H: Lewis Diagrams

-Compare the Bohr Model and Lewis Diagrams for the same element below. What is the difference between the two representations?

-Lewis only show the valence e and the chemical symbol.

-Lewis Diagrams require dots to be placed in cardinal directions (E, N, W, S) and to be paired only after the fifth e is reached.

-Complete the Lewis Diagrams for F and Na.

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1. Lewis Diagrams and Ion Rules

-Positive ions, like Na, have one e removed for each positive charge.

-Negative ions, like Cl, have one e added for each negative charge.

-Draw your own Lewis diagram for the following ionic compounds:

a) MgO b) BaBr2

2. Lewis Diagrams and Covalent Compounds and Molecules

-Shared e are drawn as a straight line.

-Draw your own Lewis diagrams for the following covalent molecules.

a) H20 b) NH3 c) CH4

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3. Lewis Diagrams and Diatomic Molecules

-Examine the diagram right. What is a diatomic molecule?

-Pair of atoms joined by a covalent bond.

-Why do diatomic molecules form?

-More stable as valence is full.

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