Atoms
What is an atom? An atom is the smallest particle of matter. It cannot be divided chemically.
An atom is very small. How small? Consider the following examples.
- A sheet of paper is about a million atoms thick.
- A drop of water can contain as many as 10 sextillion atoms.
- The diameter of the period at the end of this sentence is the length of at least 50 trillion atoms lined up in a row.
Check out this great site, it shows exactly how small an atom really is.
http://learn.genetics.utah.edu/content/begin/scale/
Rutherford's atomic modelIn this model, a small and dense nucleus contains the entire positive charge of the atom, while the eletrons, lightweight and negatively charged, are scattered randomly in a large space around the nucleus.
Rutherford-Bohr atomic modelThis model consists of a very small nucleus surrounded by electrons moving a series of orbits.
Simplified atomic modelResearch by Chadwick, in 1932, led to the addition of the neutron to the Rutherford-Bohr model.
An electron is one of the particles that make up an atom. It is negatively charged.
Cathode rays are identical regardless of the metal used to make the cathode. Thomson concluded that they are therefore common to all elements.
The proton is one of the particles that make up an atom. It is found in the nucleus and carries a positive charge.
THE HYDROSPHERE.
More than two thirds of the Earth's surface is covered in water, filling oceans, seas, lakes and rivers. Water is also found underground, in the atmosphere (in the form of a vapour) and in glaciers (in the form of snow and ice). No wonder the Earth is nicknamed the "Blue Planet"! The later of water enveloping the Earth-on, in and above it-is called the hydrosphere. In short, the hydrosphere is the Earth's outer layer of water, uniting water in all its states: liquid, solid and gas.
INDLAND WATERS are all the freshwater bodies found on continents, uniting rivers, lakes and groundwater.
A WATERSHED is an area of land in which all inland waters drain into the same larger body of water.
Many aspects of the sourrounding land and climate can affect how the water flows within a watershed, either slowing down the flow by placing obstacles in the water's path or acceleratings its course.
- topography: the shape, slope and terrain of the area. For example, steeply sloped land drains easily.
- geology: the type, depth and structure of the rock. For example, water flows more easily through the holes and gaps in crushed rock than through compact clay.
- climate: rain or snowfall, winds and temperature. For example, when it rains, the surface-water runoff is slowed by wooded areas on riverbanks. Rainwater flows into streams and rivers less rapidly.
- agriculture, industrial and urban development. For example, a dam can prevent water from flowing freely.
THE OCEANS
The continents divide the ocean waters covering the Earth into five main areas: the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, the Artic Ocean and the Southern Ocean.
Many factors can influence water temperature, including the following:
DEPTH. Example: Sunlight penetrates the upper layers of the oceans and warms the water.
THE SEASONS. Example: In the winter, the ocean loses some of the heat it stored during the summer.
LATITUDE. Example: Surface waters reach mean temperatures between 25 degree Celcius at the equator and between 12 degree Celcius and 17 degree Celcius in temperate zones.
SALINITY is a measure of the amount of salt dissolved in a liquid.
OCEAN CIRCULATION.An ocean current is the movement of seawater in a certain direction. Ocean circulation is the combined effect of all the currents that move across the oceans.
SURFACE CURRENTS are mostly wind-driven. These currents move horizontally, usually in the first 400 m of water below the surface.
SUBSURFACE CUIRRENTS. At depths of more than 800 m, winds no longer affect the ocean circulation. Deep currents prevail. These movements of water are mostly due to variations in density between water layers.
THERMOHALINE CIRCULATION is responsible for major transfers of heat around the world. Without it, the differences in temperature between the equator and the poles would be much more dramatic. In fact, the ocean is as essential as the atmosphere in regulating the Earth's climate.
The Biosphere
- the biosphere is the layer around the Earth containing all living organisms. Chemicals elements essential to life are carbon, nitrogen, phosphorus, sulfur, etc... and they are all circulating around the Earth. Example: they get absorbed by plants; animals eat the plants; then carnivores eat herbivores, leading into a never ending cycle.
Biochemical Cycles
- The steps in the processes by which an element such as carbon passes through one environment (example: photosynthesis) to the next (example: fossil fuels) and eventually returns to it's original environment (example: photosynthesis).
- biological processes: cellular respiration and digestion
- geological processes: rock erosion and sedimentation
- chemical processes: combustion and photosynthesis.
Biomes
- large regions in the world with distinctive climates, wildlife and vegetation.
Aquatic biomes: salinity, turbidity (water clarity), temperature, direction/strength of current, presence of O2 (respiration) and CO2 (photosynthesis), solar energy (how much), nutrients (type and quantity), and water depth.
Terrestrial biomes: latitude, soil type, altitude, solar energy (how much), temperature, winds, precipiation, and proximity of bodies of water.
THE CYCLES:
Carbon Cycle
[1] photosynthesis: plants take CO2 out of the atmosphere
[2] ingestion: carbon exchange from plants to animals
[3] respiration: animals/plants exhale CO2 into the atmosphere
[4] decomposition of waste: organisms decompose waste producing CO2
[5] forest fires: combustion transforms carbon into CO2
[6] shells and skeletons: CO2 + Ca = CaCO3
[7] carbonate rock: shells and skeletons accumulate on the ocean floor to form carbonated rock (limestone)
[8] volcanic eruptions: carbonate rock release CO2 when melted by magma
[9] fossil fuels: carbon from dead organisms that fell into the ocean floor are buried by sediment changing into fossil fuels (coal and oil)
Nitrogen cycle
[1] nitrogen fixation: bacteria in the soil takes nitrogen from the atmosphere and convert it to nitrates, some ammonia reactions with hydrogen create ammonium
[2] nitrification: bacteria oxidizes ammonium to form nitrites, and other bacteria oxidizes nitrites to form nitrates
[3] nitrogen absorption by plants/animals: plants draw ammonium and nitrates, herbivores eat plants, and carnivores eat herbivores
[4] decomposition of waste: bacteria and fungi (mushrooms) break down nitrogen found in plant/animal waste producing nitrites, which dissolves to form ammonia
[5] denitrification: bacteria convert nitrites into nitrogen which returns into the atmosphere
BUT what the hell is nitrogen for?
- needed to make DNA
- amino acids which make up proteins (muscles)
Chapter 6 part 1
The Lithosphere
- The lithosphere is the hard shell of the Earth, consisting of the crust and the topmost part of the upper mantle.
This hard shell covering our planet is only about a hundred kilometres thick on average. The Lithosphere contains minerals and rocks that have been essential to the development of human civilization. It is the source of building materials, metals of all kinds and even precious stones for jewellery.
- Minerals are solid inorganic substances with clearly defined composition and properties. Minerals must exist naturally on Earth; they cannot be manufactured. Most minerals have an ordered atomic structure: their atoms are organized in the form of identically shaped crystals.
Because minerals are consistently made up of the same elements, forming crystals of a specific shape, minerals exhibit certain well-defined properties, such as hardness, transparency, colour and streak. More than 4000 differnet minerals are known to exist on Earth.
Mineral Classification:Geologists classify minerals according to their properties such as colour, streak, transparency, and hardness.
* COLOUR *The element that gives them their colour is part of their chemical composition. They are called idiochromatic minerals. Other minerals may vary in colour, so they are described as allchromatic. If they were chemically pure, allochromatic minerals would be colourless, but minute quantities of impurities give them different colourings.* TRANSPARENCY *Transparency is the property by which a substance allows light to pass through it. Some minerals let light pass straight through them; they are transparent. Other let light through, but its impossible to distinguish an object through them; they are translucent. Still others let no rays through at all; they are opaque.* STREAK *When a mineral is rubbed on a surface of unglazed porcelain, it leaves a powder trace. The colour of the powder may be different from that of the mineral itself, but it is always the same for that mineral. This trace is called a streak and is considered one of the mineral's characteristics. Idiochromatic minerals leaves a brightly coloured powder. Allochromatic minerals leave a white or pale powder.* HARDNESS *Hardness depends on the strength of the bonds uniting the atoms in a mineral. The Mohs scale assigns a value from 1 to 10 to a mineral to indicate its hardness, measured by its resistance to scratching. 
