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TTHHEE SSTTAATTEESS OOFF MMAATTTTEERR
AAss tteemmppeerraattuurreess iinnccrreeaassee,, wwaatteerr iinn tthhee ffoorrmm
ooff aa ssoolliidd ((iiccee)) ttuurrnnss iinnttoo aa lliiqquuiidd aanndd
eevveennttuuaallllyy aa ggaass ((sstteeaamm)). AAss tteemmppeerraattuurree
ddeeccrreeaasseess mmaatttteerr iinn tthhee ffoorrmm ooff aa lliiqquuiidd
ttuurrnnss iinnttoo aa ssoolliidd ((iiccee)).
Editor's Notes
All matter is made up of tiny pieces called atoms. Although atoms are very small, they are made up of even smaller particles called protons, neutrons, and electrons. Electrons and protons are charged particles. Neutrons are neutral, or uncharged.
Electrons have a charge which we call negative. Protons have an opposite and equal charge which we call positive. The attraction of positive to negative charges holds the atom together. The protons and neutrons exist at the center of the atom, called the nucleus. Electrons surround the nucleus.
Elements are substances that cannot be separated into simpler substances. Salt is made up of the elements sodium and chloride. Water is made up of the elements hydrogen and oxygen.
The smallest particles of matter are called atoms. Remember the carrot from the other chapter. If you continue to chop a carrot into smaller and smaller pieces, eventually you would reach a point where you could not cut up the carrot anymore, but still have carrot. You would then have molecules of carrot. The same applies to elements. If you continually cut up a piece of aluminum, you will reach a point that you could no longer divide it. These are aluminum atoms. An atom is the smallest particle of an element that has the properties of that element. Some properties of aluminum are: shiny, silver colored, fragile, and thin. Each element has its own type of properties.
Chemists use symbols to represent elements. A symbol is a letter or picture used to represent something. Chemists use one or two lettters to represent elements. The symbol for aluminum is Al. The symbol for oxygen is O. The symbol for oxygen is O. "O" stands for one atom of oxygen. Oxygen stoms are joined in pairs. To write a pair of oxygen atoms using symbols, we use the symbol O and the number 2. Oxygen would be (O2). The 2 is a subscript. "Sub" means "below". The 2 is written to the right of and below the O. A pair of oxygen atoms is a molecule of oxygen. A molecule is the smallest particle of a substance that exists independently. Molecules of most elements are made up of only one of atom of that element. Oxygen, along with nitrogen, hydrogen, and chlorine are made up of two atoms. Look at the model of oxygen above. The two balls represents the two oxygen molecules. The oxygen molecules are bonded or stuck together. We will learn about bonds later.
Compounds
A compound is a substance formed when two or more elements are chemically joined. Water, salt, and sugar are examples of compounds. When the elements are joined, the atoms lose their individual properties and have different properties from the elements they are composed of. A chemical formula is used a quick way to show the composition of compounds. Letters, numbers, and symbols are used to represent elements and the number of elements in each compound
Examples- Raisin Bran Cereal, handful of coins.
Raisins remain raisins and do not change into bran when mixed. Quarters remain quarters and nickels stay nickels regardless
The molecules in a solid are locked in place by invisible forces. These particles are not free to move around ... all they can do is vibrate. The more energy they have, the more they vibrate. If you apply more and more heat to a solid, the particles vibrate faster and faster. Eventually the particles will have enough energy to break free of the forces holding them in line .... When that happens, the solid turns to a liquid! The particles are still held by forces that keep them grouped together, but now they are free to vibrate and move around within the substance. As you apply more heat energy, the particles move around faster. As a liquid, the substance can hold a lot more heat. The more heat you add, the faster the particles move around. That's why liquids have a higher specific heat capacity than solids. Eventually, however, you will have made the liquid very hot, and those liquid particles will be moving around really fast! Every once in a while, a very energetic particle will get enough energy to escape completely from the liquid ... and particle by particle, the liquid molecules will escape from the liquid completely. This process occurs when you boil a liquid ... the liquid evaporates. This means that the particles escape, and are no longer part of the liquid substance ... they are free to wander around on their own. Particles that can do this are called a gas. Substances in gaseous form are made of particles that are free to move wherever they want, as fast as they want. The more heat you apply, the faster they move ... there's no holding them back! Gases have the highest specific heat capacity of any substance. You can pump as much heat into a gas as you want, and it will store that heat as the kinetic energy (movement) of its particles.
