Standards Project

Charlotte Koberg

Table of Contents

Structure of Atoms

a. Atomic Structure

b. Atomic Nucleus

c. Isotopes

Structure and Properties of Matter

a. Valence Electrons

b. Chemical Bonds

  • Ionic
  • Covalent
  • Hydrocarbon Compounds

c. Periodic Table/Trends

d. Physical/Chemical Properties of Chemical Compounds

e. States of Matter

f. Relationship between Pressure and Volume of gases

Chemical Reaction

a. Conservation of Matter

b. Common Reactions/Types of Reactions

c. Acids and Bases

Problem Solving

a. Metric System Conversions

b. Stoichiometry

Structure of Atoms

Atomic Structure- In every atom, there is a nucleus, protons, neutrons and an electron cloud

Nucleus

The nucleus is composed of neutrons, which have a neutral charge and protons, which have a positive charge. When these two particles join together, they form the nucleus. It is also surrounded by electrons. The nucleus essentially contains all of the mass of the atom, because the neutrons and protons have a mass close to 1 while an electron is about 2,000 times smaller in mass. If the amount protons do not equal to the amount of electrons, then the atom is an ion.

Isotopes

An isotope is a different version of an element, because the number of neutrons vary. Since the number of neutrons vary, that affects the mass of the nucleus. One way to realize there is an isotope, is from the number given after a symbol or name, because that tells you the mass of the element. For example, Carbon usually just has 6 neutrons, while Carbon-13 still has 6 protons, but it now has 7 neutrons, and 6 plus 7 equals 13, which is where the mass comes into play.

Structure and Properties of Matter

Valence Electrons

Electrons in the outermost shell are valence electrons. Valence electrons on an atom can be gained or lost during a chemical reaction. On the periodic table, the group number represents the number of valence electrons an element has. As you move across the periods, the number of valence electrons increase, but when you drop down to a new period, the number starts at one again, but increases as it moves across again.

Examples on Finding the Number of Valence Electrons

Chemical Bonds

Ionic
  • Strongest type of bonding, crystal lattice structure, occurs between metals and nonmetals or polyatomic ions, they are formed from the transfer of electrons to attain a full outer shell, most polar bond
  • Properties: high boiling/melting points, they are soluble in water and high conductors in solutions, no odor
  • Determination: if the first element given is to the left of the stair step, it is ionic

Covalent

  • It is determined by polarity, which describes the distributions of electrons in a bond
  • Nonpolar Covalent: the least polar bond, has even sharing of electrons
  • Polar Covalent: middle polar bond, has uneven sharing of electrons
  • Properties: low conductivity, low boiling/melting points, odor
  • Determination: if the first element given is to the right of the stair step, it is covalent

Hydrocarbon Compounds

Only hydrogen and carbon elements are used

  • Alkanes: single bond, saturated, maximum number of hydrogens, carbons 1-4 used
  • Alkenes: 1 double bond, unsaturated, carbons 2-5 used
  • Alkynes: 1 triple bond, unsaturated, carbons 2-5 used

Periodic Table & Trends

  • Periodic Law: repetition of physical and chemical properties when the elements are arranged by atomic number
  • A group in the periodic table are the vertical columns, going down, groups behave the same way with their similar properties, the numbers above the group tells you how many valence electrons those elements have
  • A period is the horizontal columns, going left to right, they have the same atomic orbitals (how many shells the element has for its electrons)
  • Atomic Radius Trend (the distance from the nucleus to the outer shell of electrons): decreases from left to right when moving across the period; when moving down a group the atomic radius increases
  • Electronegativity Trend: from left to right in a period, electronegativity increases; when moving down a group, the electronegativity decreases
  • Ionization Trend: from left to right in a period; the ionization energy increases; when moving down a group, the ionization energy decreases

Organization

The periodic table is made up of;

Metals: shiny, solid, good conductors and react with acid

Non-metals: gases, brittle if solid, dull and poor conductors (exceptions: Hydrogen and Aluminum)

Metalloids: share properties of metals and non-metals, share a side with stair step

Families

Alkali Metals (1A, except Hydrogen): very reactive with metals, soft metals, not found naturally, low densities

Alkali Earth Metals (2A): reactive with metals, found in earth's crust

Halogens (7A): highly reactive, diatomic (gives the element a subscript of 2), gases

Noble Gases (8A): nonreactive, found in small quantities in the atmosphere, monatomic because of their full valence shells

Physical/Chemical Properties of Chemical Compounds

Physical Change: no new substance is created

examples: ice melting, cutting an apple, mixing a salad

Physical Properties: can be observed or measured without changing the chemical composition

examples: density, mass, color and volume

Chemical Change: new substance is formed

  • Indicators: color change, bubbles, odor, solid forming, temperature change

examples: frying an egg, metal rusitng, burning paper

Chemical Properties: observed when the substance interacts with one another

examples: flammability, reactivity with acid, reactivity with base, toxicity

Extensive Properties: external, depends on the quantity of the substance

examples: mass, volume

Intensive Properties: internal, does not depend on the quantity of the substance

examples: density, melting point

States of Matter

Solid: particles in a solid are closely compacted, they barely move, fixed volume and shape, not easily compressible

Liquid: particles in a liquid assumes the shape of the container it occupies, not easily compressible, particles slide past each other, flows easily, fixed volume

Gas: particles in a gas assume the shape and volume of the container it occupies, compressible, flows easily, particles move very fast and bounce off each other

Phase Changes

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Relationship between Pressure and Volume of gases

Absolute pressure and volume, if the temperature remains the same, are inversely proportional. This can be mathematically solved by:

P1V1=P2V2

Chemical Reactions

Conservation of Matter

Mass or matter cannot be created or destroyed

Common Reactions

Some common, everyday chemical reactions would include; rusting of iron, burning wood, mixing ingredients that cannot be separated, baking the ingredients and digestion.

Types of Reactions

1. Synthesis- when two or more substances form one product

2. Decomposition- when one substance breaks up into two or more products

3. Single Replacement- when one element replaces another in a compound

4. Double Replacement- when two compounds exchange elements

5. Combustion- when fuel is burned in the presence of oxygen to produce water vapor and carbon dioxide

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Double Replacement

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Combustion

Acids and Bases

Acids: taste sour, corrosive, react with metals to form H2, donate H+ ions

Bases: feel slippery, taste bitter, corrosive, accept the H+ ions

Litmus Paper: when using red litmus paper, and a drop of base is added, it will turn the paper blue; when using blue litmus paper, and a drop of acid is added, it will turn the paper red

pH scale: measure of hydrogen ion concentration in a solution

Conjugate acid: base plus H+

Conjugate base: acid minus H+

Acid base reactions: forms water and salt, neutralization, no excess acid or base

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Problem Solving

Metric System Conversions

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Stoichiometry

The calculation of the quantities of elements involved in chemical reactions.

Mole ratio- a relationship connecting or relating the molar amounts of two substances in a balanced equation

Steps for Stoichiomety

1. Balance the equation

2. Identify the starting point

3. Convert to moles

4. Multiply by mole ratio

5 Convert to ending point

Example of Stoichiometry

Question: Oxygen gas can be produced by decomposing potassium chlorate using the reaction below. If 138.6 g of KClO3 is heated and decomposes completely, what mass of oxygen gas is produced?

Equation: KClO3 --> KCl + O2


1. Balance the equation: 2KClO3 --> 2KCl + 3O2

2. Identify the starting point: 138.6 g of KClO3

3. Convert to moles: 138.6 g of KClO3 / 122 g/mol = 1.136 mol of KClO3

4. Multiply by mole ratio: 1.136 mole KClO3 * 3 mol O2 = 1.704 mol O2

2 mol KClO3

5. Convert to ending unit: 1.704 mol O2 * 32 g O2 = 5453 g O2 is produced