Chemistry - Mass Number

The MASS NUMBER, A, equals the sum of the number of protons and neutrons present in the nucleus.

Chemistry - Molarity

M: Molarity is defined as the number of moles of solute per liter of solution.

Chemistry - Homogeneous Equilibria

Equilibria that involve only a single phase.

Chemistry - Beta Particles

BETA particles are the same as electrons, but originate from within the nucleus and have the nuclear symbol:
0
e
-1

Chemistry - Chemical Thermodynamics

CHEMICAL THERMODYNAMICS (thermo = heat, dynamics = movement, so, heat
movement) is the study of energy and its interconversions.

Chemistry - Exothermic Change

EXOTHERMIC change is one in which thermal energy is given off. The
temperature of the system goes up.

Chemistry - Electrons

ELECTRONS are extremely small particles (much smaller than an atom) with a unit negative charge.

Chemistry - Mass%

MASS % is the ratio of the mass of a component to the total mass of a sample times 100.
Mass % = (# g solute / # g solution) x 100.

Chemistry - Dilute Solutions

DILUTE solutions have a relatively small amount of solute.

Chemistry - 2nd Law of Thermodynamics

SECOND LAW OF THERMODYNAMICS: In any spontaneous process there is always an increase in the entropy of the universe

Chemistry - Chemical Kinetics

CHEMICAL KINETICS is the study of how fast reactions occur.

Chemistry - Homogeneous Mixtures

HOMOGENEOUS MIXTURES have only one phase. They have the same properties throughout a sample, although the properties of different samples may be
different.

Chemistry - Surroundings

SURROUNDINGS: Everything outside of the system under study.

Chemistry - Concentrated solutions

CONCENTRATED solutions have a relatively large amount of solute.

Chemistry - Strong Bases

The hydroxides of all IA metals and of Ca, Sr, Ba, (and Ra) in Group IIA are strong electrolytes.

Chemistry - Strong electrolytes

Completely ionized in solution - in the conductivity apparatus, the light is bright.

Chemistry - Unsaturated Solutions

UNSATURATED solutions contain a lower concentration of solute than a saturated solution.

Chemistry - Spontaneous Change

SPONTANEOUS change is one that takes place by itself.

Chemistry - Nonspontaneous Change

NONSPONTANEOUS change can be made to take place by supplying energy.

Chemistry - <=> symbol

<=>: This symbol is used for the double arrow of an equilibrium reaction.

Flora and Fauna

Keeping wildlife or growing green things are a wonderful addition to a unit study. There´s nothing like actually seeing the topic of your study up close. We have hatched butterflies and sea monkeys, grown corn and other plants and will be hatching tadpoles this spring.

How to solve tough science problems?

Tough science problems are less intimidating once you
analyze them - once you figure out what kind of problem it is and what kind of principles and procedures are relevant to solving it. To be an expert problem solver, look for essentials. Get in the habit of asking:

* What is the problem about? What are you being asked to find?

* What information is relevant? What principles are
relevant?

* What do you know about similar problems? How did you solve those? What´s different here?

* What methods should you follow to use the information you have to solve the problem?

* Does your solution makes sense?

The amateur problem solver starts plugging numbers into equations right away. He tries to solve the problem by brute force. Expert problem solvers get the lay of the land first. To be an expert, know what you´re doing - and why.

Chemistry - Solute

A SOLUTE is the solution component present in a smaller amount than the solvent.

Newspaper Activities

Have students look up the high and low temperatures for your community. Compare the temperature where you live with other parts of the country. Have them find the highest and lowest temperature.

Extend this activity by having students write about the climate in either the city with the highest temp or the lowest temp.

Chemistry - Nuclear Equations

NUCLEAR EQUATIONS show the changes that take place in the nuclei. They are similar to chemical equations in that reactants are shown to the left of the arrow and products are shown to the right of the arrow.

Chemistry - Atomic Number

The ATOMIC NUMBER, Z, is the number of protons present in the nucleus of an atom. In a neutral species, it is equal to the number of electrons present in the atom.

Chemistry - Acid

A substance that increases the concentration hydrogen ions when dissolved in water.

Chemistry - Gamma Rays

GAMMA rays are high energy (higher energy and shorter wavelength than x-rays) electromagnetic radiation which are usually given off when a nuclide decays. Gamma rays are usually not shown in nuclear equations since they have no mass or charge.

Chemistry - Equilibrium

EQUILIBRIUM occurs when the forward rate of change equals the reverse
rate of change.

Chemistry - Acid Dissociation Constant or Acid Ionization Constant

It has the symbol Ka and is the equilibrium constant expression for the ionization of a weak acid.
For any weak acid, HA, Ka = [H^+][A^-] / [HA].

Chemistry - Nucleus

The NUCLEUS is at the center of the atom and is small, dense and positively charged.

Chemistry - Strong Acids

HCl, HBr, HI, HClO4, HNO3, and H2SO4 are all strong electrolytes. All other common acids are weak electrolytes.

Chemistry - Nonelectrolytes

No ions present in solution - in the conductivity apparatus, the light is out.

Chemistry - Entropy

ENTROPY is a quantitative measure of disorder/randomness in a system.

How to teach the impact of the shape of earth on weather?

Younger students may have a problem to understand the impact of the shape of Earth. One of the ways to teach them, is through a "pick" to a "sister-class" in the Southern Cone (or the Northren, if you´re in the Southern). They will see and learn that while we have winter, they have summer (make them write an essay about the different impacts, for example, Chritmas in the summer).

Chemistry - Formula - Volume %

VOLUME % = (volume solute / volume solution) x 100.

Chemistry - Isotopes

ISOTOPES are elements with the same number of protons, but different numbers of neutrons, that is the atomic number is the same, but the mass numbers are different.

Chemistry - Le Chatelier´s Principle

LE CHATELIER´S PRINCIPLE: If an equilibrium is *disturbed*, - changed in some way - processes occur that tend to partially counteract the *disturbance*,
and thus bring the system to a new position of equilibrium. The system *shifts* so as to reduce the effect of the change.

Chemistry - Isotopes

ISOTOPES are elements with the same number of protons, but different numbers of neutrons, that is the atomic number is the same, but the mass numbers are different.

Chemistry - Nuclear Symbol

A NUCLEAR SYMBOL is a symbol for an individual nuclide. It has the form:

mass number - A
chemical symbol - X
atomic number - Z

Chemistry - Percent Dissociation or Percent Ionization

Percent dissociation or Percent ionization: Percent is equal to the part divided by the whole times 100: So, percent ionization is equal to the fraction of the solute that is ionized times 100. For a weak acid,
this gives: [A^-]eq
% ionization (HA) = -------- x 100
[HA]init

Where [A^-]eq is the concentration of the anion at equilibrium, and [HA]init is the initial concentration of the weak acid.

Chemistry - Radioactive Decay

RADIOACTIVE DECAY are nuclear reactions that involve the protons and neutrons that make up the nucleus.

Chemistry - Alpha Particles

ALPHA particles are helium nuclei and have the nuclear symbol:
4
He
2

Chemistry - Vapor Pressure

EQUILIBRIUM VAPOR PRESSURE or VAPOR PRESSURE: The pressure of the vapor in equilibrium with a liquid - depends on the strength of the
intermolecular forces of the liquid and on the temperature.

Chemistry - Nucleons

NUCLEONS is a term used to refer to both protons and neutrons in the nucleus.

Chemistry - Dynamic Equilibrium

DYNAMIC EQUILIBRIUM: the rates of change in the forward and reverse directions are equal.

How To Use The Scientific Method

The Scientific Method is a systematic way to find answers to questions that interest you. The following five steps will make the documentation of your science experiments easier.

1. Question: Make observations and develop your question. The question should be about what you are interested in learning or what you want to know.
2. Hypothesis: State your hypothesis. Your hypothesis is your educated guess about what you think will happen.
3. Method: The method is the process or steps of your experiment. This should be very detailed and include materials needed.
4. Results: The results are the facts or data that you collect from your experiment.
5. Conclusion: In the conclusion, you explain why you think the experiment happened the way it did. Include whether the results supported your hypothesis or not.

Chemistry - Supersaturated Solutions

SUPERSATURATED solutions contain more than the equilibrium concentration of solute that is present in a saturated solution.

Chemistry - Endothermic Change

ENDOTHERMIC change is one which thermal energy is absorbed. The temperature of the system goes down.

Chemistry - Universe

UNIVERSE: the system and the surroundings.

Homeschooling - Dissection

Try dissecting a freshly caught trout for a unit on Fish. I had a friend who brought home a dead rabbit discovered on a morning walk for her children to dissect during the day´s homeschool session. Always wear gloves and take safety precautions when dissecting wild specimens. See my link for virtual frog dissections to get some practice.

Chemistry - Saturated Solutions

SATURATED solutions contain as much solute that will dissolve at a given temperature in the presence of excess solute

Chemistry - Solvent

A SOLVENT is the substance (usually a liquid) which is the major component of a solution.

Chemistry - 3rd Law of Thermodynamics

THIRD LAW OF THERMODYNAMICS: the entropy of a perfect crystal at 0 Kelvin in zero.

Chemistry - Valence Electrons

VALENCE electrons are the electrons in the outer shell that are involved in chemical reactions.

Chemistry - Weak Electrolytes

Partially ionized in solution - in the conductivity apparatus, the light is dim.

Chemistry - Protons

PROTONS are small particles with a unit positive charge present in the
nucleus.

Preventing Science Slips

1. Plan carefully. Write out even the minutest detail ahead of time.
2. Allow time for last minute difficulties. Hardly anything ever works exactly right the first time. Make sure that you don´t try to cram a 25 minute experiment into 15 minutes!
3. Trust your instincts. If the experiment seems like it might be dangerous or faulty, check with an expert before proceeding.
4. Follow instructions exactly. Now is not the time to cut corners and it could even be dangerous.
5. Don´t be afraid to elaborate.While this may seem contradictory to the preceding tip, feel free to expand the experiment where safety is not a concern. Part of the discovery process is asking "What would happen if we did this?".
6. Turn failure into learning oppotunities. If the experiment fails, instead of chucking it, go back and search for reasons why it failed.

Chemistry - pH

pH is defined as the negative of the base ten logarithm of the molar concentration of hydrogen ion. pH = -log[H^+]. Remember, the first # in a pH value is just telling the power of 10 or the # of decimal places. So, use the # of digits after the decimal point to determine the # of significant figures for [H^+].

Chemistry - Base

A substance that increases the concentration of hydroxide ions when dissolved in water.

Chemistry - 1st Law of Thermodynamics

FIRST LAW OF THERMODYNAMICS: the energy of the universe is constant - energy cannot be created or destroyed.

Chemistry - Electrolytes

Compounds that conduct elecricity when dissolved or melted. Three types of compounds are electrolytes: acids, bases and salts. Substances maybe classified as Strong Electrolytes, Weak Electrolytes, or Nonelectrolytes.

Chemistry - Molarity Formula

MOLARITY (M) = moles of solute / (volume of solution in L).

Chemistry - System

SYSTEM: The part of the universe under study