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Describes periodic trends that can be observed on the periodic table. Created for CHEM 2061, University of Colorado- Denver, Spring 2010 Please do not reproduce or use these images without my permission Bibliography: Chemistry: A Molecular Approach Tro 1e http://en.wikipedia.org/wiki/Periodic_trends

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Quantum Mechanical

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Bohr Model

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Solar System Model

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Dalton Model

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4 Element Model

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Periodic Table of Elements: Los Alamos National Laboratory

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Elements can generally be described as either metals or nonmetals. Metal elements are usually good conductors of both electricity and heat. The dividing line between metals and non-metals is not hard and fast, thus the distinction between "Post-transition metals" and "Metalloids" is represented differently on different versions of the Periodic Table.

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Uploaded by teachinglearninguoit on 2010-10-27.

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Periods

The only trend of periods are as you go across a period, electrons are added to the same energy level. At the same time, protons are being added to the nucleus. The concentration of more protons in the nucleus creates a "higher effective nuclear charge." In other words, there is a stronger force of attraction pulling the electrons closer to the nucleus resulting in a smaller atomic radius.

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Groups/Families

The elements in the groups or families share the same characteristics like chemical reactivity and composition like the metals or non metals

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Reactivity is the tendency of a substance to undergo chemical reaction, either by itself or with other materials, and to release energy.

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Lewis Dot Diagram

Lewis diagrams are based on the amount of outer electrons and they are represented by dots surrounding the elements symbol with a maximum of 8

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AVERAGE ATOMIC MASS

The average atomic mass of an element is the sum of the masses of its isotopes, each multiplied by its natural abundance (the decimal associated with percent of atoms of that element that are of a given isotope).

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Plum Pudding Model

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The heat of the reaction (Delta H) is less than zero. Energy of reactants is greater than the product and therefore, energy is released.

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Democritus Model

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The heat of the reaction (Delta H) is greater than zero. Energy of reactants is less than the product and therefore, energy is absorbed.

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Before we dive into solutions, let's separate solutions from other types of mixtures. Solutions are groups of molecules that are mixed and evenly distributed in a system. Scientists say that solutions are homogenous systems. Everything in a solution is evenly spread out and thoroughly mixed. Heterogeneous mixtures have a little more of one thing (higher concentration) in one part of the system when compared to another.

Let's compare sugar in water (H ₂ O) to sand in water. Sugar dissolves and is spread throughout the glass of water. The sand sinks to the bottom. The sugar-water is a homogenous mixture while the sand-water is a heterogeneous mixture. Both are mixtures, but only the sugar-water can also be called a solution.

Pretty much. Solutions can be solids dissolved in liquids. When you work with chemistry or even cook in your kitchen, you will usually be dissolving solids into liquids. Solutions can also be gases dissolved in liquids, such as carbonated water. There can also be gases in other gases and liquids in liquids. If you mix things up and they stay at an even distribution, it is a solution. You probably won't find people making solid-solid solutions. They usually start off as solid/gas/liquid-liquid solutions and then harden at room temperature. Alloys with all types of metals are good examples of solid solutions at room temperature.

A simple solution is basically two substances that are evenly mixed together. One of them is called the solute and the other is the solvent. A solute is the substance to be dissolved (sugar). The solvent is the one doing the dissolving (water). As a rule of thumb, there is usually more solvent than solute. Be patient with the next sentence as we put it all together. The amount of solute that can be dissolved by the solvent is defined as solubility. That's a lot of "sol" words.

Science has special names for everything. They also have names for the different types of homogenous mixtures. Solution is the general term used to describe homogenous mixtures with small particles. Colloids are solutions with bigger particles. Colloids are usually foggy or milky when you look at them. In fact, milk is an emulsified colloid.

You may also hear about colloids if you study soil. While milk is an organic colloid, soils can be made up of inorganic colloids, such as clay.

More on Solutions in Part II...

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Before we dive into solutions, let's separate solutions from other types of mixtures. Solutions are groups of molecules that are mixed and evenly distributed in a system. Scientists say that solutions are homogenous systems. Everything in a solution is evenly spread out and thoroughly mixed.

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1. Introduction

2. Types of Saturation

3. Factors Affecting Saturation

4. Other Related Topics

5. Outside Links

6. References

7. Contributors

Introduction

When solid solute ( substance or particles) and liquid solvent are mixed, the only possible reactions are dissolution and crystallization.

Dissolution is the dissolving process of the solid solute.

Crystallization is the opposite, causing the solid solute to remain undissolved.

Types of Saturation

Kinds of Saturation

Definition

Saturated Solution

A solution with solute that dissolves until it is unable to dissolve anymore, leaving the undissolved substances at the bottom.

Unsaturated Solution

A solution ( with less solute than the saturated solution) that completely dissolves, leaving no remaining substances.

Supersaturated Solution

A solution ( with more solute than the saturated solution) that contains more undissolved solute than the saturated solution because of its tendency to crystallize and precipitate.

Example 1: Saturated Solution

Example 1: Above is illustrated an example of a saturated solution. In Figure 1.1-1.3, there is a constant amount of water in all the beakers. Figure 1.1 shows the start of the saturation process, in which the solid solute begins to dissolve ( represented by red arrows). In the next beaker, Figure 1.2, much of the solid solute has dissolved, but not completely, because the process of crystallization ( represented by blue arrows) has begun. In the last beaker, Figure 1.3, only a small amount of the solute solvent remains undissolved. In this process, the rate of the crystallization is faster than the rate of dissolution, causing the amount of dissolved to be less than the amount crystallized.

Example 2: Unsaturated Solution

Example 2: Next, an unsaturated solution is considered. In Figure 2.1-2.3, there is a constant amount of water in all the beakers. Figure 2.1 shows the start of the process, in which solid solute is beginning to dissolve ( represented by red arrows). In the next beaker, shown in Figure 2.2, a large amount of solute has dissolved. The size of the red arrows are much larger than those of the blue arrows, which means that the rate of dissolution is much greater than rate of crystallization. In the last beaker, shown in Figure 2.3, the solute solvent has completely dissolved in the liquid solvent.

Example 3: Supersaturated Solution

Example 3: This is an example of a supersaturated solution. In Figure 3.1-3.3, there is a constant amount of water in all the beakers. Figure 3.1 shows a beaker with more solid solute than in the saturated solution ( Figure 1.1) dissolving. In Figure 3.2, solid begins to crystallize as it slowly decreases the rate of dissolution. In the last picture, Figure 3.3, the solids become a crystallized form which begins to harden.

Factors Affecting Saturation

The solubilities of ionic solutions increase with an increase in temperature, with the exceptions of compounds containing anions.

Finely divided solids have greater solubilities.

In contrast to the solubility rate, which depends primarily on temperature, the rate of crystallization depends on the concentration of the solute at the crystal surface.

In a still solution, concentration builds at the solute surface causing higher crystallization; therefore, stirring the solution prevents the build up, maximizing the net dissolving rate.

The net dissolving rate is defined as the dissolving rate minus the crystallization rate.

If the rates of solubility and crystallization are the same, the solution is saturated, and dynamic equilibrium is reached.

Le Chatelier's principle predicts the responses when an equilibrium system is subjected to change in temperature, pressure or concentration. This principle states the following:

For an increase of temperature, solubility increases which causes an endothermic reactions.

For an decrease of temperature, solubility decreases which causes an exothermic reactions.

Adding an inert gas to a constant-volume equilibrium mixture has no effect on the equilibrium.

An increase in the external pressure causes a decrease in reaction volume and shifts equilibrium to the right.

References

Petrucci, Harwood, Herring. General Chemistry: Principles & Modern Applications. 8th ed. Upper Saddle River, New Jersey: Pearson/Prentice Hall, 2002.

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Introduction Types of Saturation Factors Affecting Saturation Other Related Topics Outside Links References Contributors When solid solute ( substance or particles) and liquid solvent are mixed, the only possible reactions are dissolution and crystallization. Dissolution is the dissolving process of the solid solute. Crystallization is the opposite, causing the solid solute to remain undissolved.

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midsize particles that do not settle out and appear cloudy

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BEHAVIOR OF AN ATOM

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Categories

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A material is composed of only one type of particle

Gold is an example of a pure substance.

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ISOTOPES

Each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element.

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DIAGRAM OF THE ATOM

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ATOMIC THEORY TIMELINE PART 2

1911 Model by Rutherford "Solar System Model", An atom is spherical in shape with a tiny central nucleus containing all of the positive charge and most of the mass, with electrons orbiting in mostly empty space. Technology used was Gold Foil experiment using recently discovered radioactive material

1913 Model by Bohr Similar to Rutherford's except: When the atom receives energy from an outside source, an e- jumps from a lower energy level to a higher one. As the e- returns to the lower level, energy in the form of light is released technology used was Hydrogen Spectrum

20th Century Model of Quantum Mechanics, The atom consists of a central nucleus containing protons and neutrons together with electrons existing outside of the nucleus having definite energy but no definite definite orbits around the nucleus

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BY CHARLES

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Andrea, Jackie, Tyren, and Charlie

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Jackie

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ATOMIC THEORY TIMELINE

450 BC Model: 4 Element, All matter was made up of a combination of four basic components: Earth, Water, Air, and Fire

400 BC Model by Democritus, The ultimate underlying structure to matter is the basic smallest unit of matter: "atomos"- not cuttable concept was developed by reason

1803 Model by Dalton, An atom of any givien element has its own fixed mass

1898 Model by JJ Thompson "Plum Pudding Model", An atom is spherical in shape and consists of a thin cloud of positively charged particles sprinkled throughout technology used were Cathode ray tubes