Lecture 6-Energy Flashcards
About atomic structure
The way matter behaves, for example, the way one chemical reacts with another chemical suggests that all matter is made up of very small particles. The particles may be atoms, combinations of atoms called molecules, or electrically charged particles called ions. These particles are too small to be seen yet scientists have been able to deduce their structure, create models of how they are arranged in different substances, and predict how they will react, indicating that the models are fairly accurate.
about the atom
The fundamental particle of all matter. is defined as the smallest part of an element that can exist and still have the properties of the elements. Examples of elements are carbon, hydro- gen, oxygen, iron, copper, sulphur, aluminum and so on.
What are atoms made up of?
made up of electrons (with one negative charge), protons (positively charged) and neutrons (no charge), sometimes called sub- atomic particles.
Where are protons and neutrons found?
The protons and the neutrons are found in the nucleus of the atom and the electrons are outside the nucleus and move around it.
About electrons, protons and neutrons
the number of protons (and neutrons) in the nucleus is always the same as the number of electrons in the outer ring so they are balanced (negative and positive charges cancel). Sometimes electrons escape from the outer ring or an additional electron enters the atom. The result is a positively or negatively charged particle called an ion.
What do atoms use to form their bonds?
their outer shells. What is important is that they hold different atoms together to form combinations of atoms which are referred to as molecules. For example, sodium atoms and chloride atoms are bonded together in sodium chloride, which is common salt. The way in which bonds are formed, the number of atoms, and how they are arranged contribute to the properties of different compounds. Like atoms, these bonds cannot be seen. Scientists use models to show how they imagine the atoms and bonds are arranged in molecules.
About small molecules and large molecules
Small molecules can combine to form much larger molecules. Many of the molecules found in living organisms are giant molecules (e.g. proteins) that are built up from smaller units (e.g. amino acids) into which they can be broken down again. Appropriate enzymes (specialised protein molecules) control the building up and breaking down processes. (More on enzymes later.)
Nuclear energy
The nucleus of an atom is held together by a lot of energy. For its tiny size a nucleus contains so much energy that it forms a notice- able percentage of the mass of the nucleus as a whole. Some elements have more energy in their nuclei than others. When a very large nucleus, held together by a large quantity of energy, splits into smaller fragments, some mass is lost and a corresponding amount of energy is released. A chain reaction is set off causing more and more nuclei to split. The energy appears as the kinetic energy of the fragments and when these rapidly moving fragments collide, thermal energy is produced. Early atom bombs depended on this type of chain reaction to release energy from all the nuclei at once. Nuclear power stations do not explode because controls are placed on the chain reaction so that fission (the splitting of the atoms) takes place much more slowly in an orderly fashion.
What is electricity and example
is a form of energy resulting from the existence of charged particles e.g. electrons, protons etc. An electric current is a flow of charge. The rate of flow of the electric charge is measured in amperes. Household appliances such as electric kettles run on a few amperes. Batteries in appliances such as a flashlight work by allowing a flow of current through the bulb and back to the battery. When the light is switched off the flow of charge stops.
What is a volt and an example
is the force that causes the current to flow at a particular rate (it can be compared to the way a pump forces water to flow along a pipe). The battery pumps the charge around the flashlight; different batteries have different voltages. The batteries used in some pocket radios and small flashlights have a pumping force of 1.5 volts. A car battery supplies 12 volts of pumping force to get a car started. The size of the current that a battery will pump round a circuit depends on the voltage of the battery and the conductor along which the charge must flow.
About metals
will conduct electricity. Some metals are better conductors than others. Some substances, e.g. rubber and wood, do not conduct electricity at all. Semi-conductors are substances that have conducting properties somewhere between conductors and non- conductors i.e. they are fairly good conductors under certain condi- tions.
What is a generator?
is a machine that can convert mechanical energy into electrical energy. In the generator, an electric current is created when wires are moved through a magnetic field.
What is a turbine?
turbine is an engine that drives the generator. Turbines can be driven by wind, steam, water or diesel power. Nuclear power is used to produce the steam in some power stations
What are cells?
are the basic structural and functional units of living things. They are the building blocks of which the tissues and organs of most organisms are made. Bacteria, protozoa, and yeasts are single- celled organisms; most other organisms are multi-cellular i.e. made up of many cells.
Cells and their functions
become differentiated to perform different functions. These specialised cells vary in structure to suit their functions so there is really no such thing as a typical cell. However all cells share certain characteristics. Cells also vary considerably in size but the size of an “average” cell could be about one fiftieth of a millimetre (or 20 microns)
