Atoms are the general term used to describe pieces of matter.
You are made up of billions and billions of atoms.
However, you may only find about 40 elements inside of your body.
- You would find hydrogen (H) atoms, oxygen(O) atoms, and a bunch of others. Those other atoms are made of the same basic pieces, but they are organized in different ways to make each element unique.
An atom is the smallest building block of everything that exists. The smallest object you can see under a microscope has more than 10 billion atoms .
There are over a hundred different types of atoms, that we call elements. They form the world we live in.
Common Elements
- If
you read a book, you will find a bunch of words on a page. Letters make up
those words. In English, we only have twenty-six letters, but we can make
thousands of words.
- In chemistry, you are working with around 120 elements, and
when you combine them you can make millions of molecules. Molecules are groups
of atoms bonded together in the same way that words are groups
of letters.
An "A" will always be an "A" no matter what
word it is in. A sodium (Na) atom will always be a sodium
atom no matter what compound it is in. While the atoms may have different
masses and organization, they are all built with the same parts.
If you want to do a little more thinking, start with the smallest particles of matter. Those super-tiny subatomic particles are used to create atoms.
- If you read a book, you will find a bunch of words on a page. Letters make up those words. In English, we only have twenty-six letters, but we can make thousands of words.
- In chemistry, you are working with around 120 elements, and when you combine them you can make millions of molecules. Molecules are groups of atoms bonded together in the same way that words are groups of letters.
Atoms are used to create the molecules around us. As we just learned, there are almost 120 known types of atoms. That means there are almost 120 elements that can be found in the molecules we know.
Smaller molecules can work together and build macromolecules. It just goes on. Everything you see is built from something else.
You could start really small...
- Particles of matter
- Atoms
- Molecules
- Macromolecules
- Cell organelles
- Cells
- Tissues
- Organs
- Systems
- Organisms
- Populations
- Ecosystems
- Biospheres
- Planets
- Planetary Systems with Stars
- Galaxies
- The Universe
...And finish really big.
Wow. All of that is possible because of atoms.
- For example, water has two atoms of hydrogen and one atom of oxygen.
- Plutonium is one of the heaviest atoms , about 200 times heavier than hydrogen , which is the lightest element.
Parts of the Atom
An atom consists of three parts :
protons, neutrons, electrons.
Protons and neutrons are in the center of an atom, which is called the nucleus. It is very small if you compare it with the whole atom and it has almost all of an atom’s mass.
- If an atom had a diameter of about 6 km the nucleus would only be as big as a tennis ball. The rest of the atom outside the nucleus is mostly empty.
Electrons fly around in an atom very, very quickly. They have almost no mass and travel around the nucleus millions of times every second.
The parts of an atom have electrical charges.
- Each proton carries a positive electrical charge +
- Each electron has a negative electrical charge. -
- Neutrons have no charge.
- In most cases an atom has the same number of protons and electrons. It is electrically neutral.
The energy of the nucleus keeps the electron inside the atom—just like the Earth keeps the moon in its orbit. But electrons have energy themselves. They want to break away from the nucleus. If an electron has a lot of energy it moves around farther away from the nucleus.
Electrons move around the nucleus in up to seven round paths , called shells.
- The first shell is closest to the nucleus. It can hold 2 electrons.
- The second shell can hold 8, the third 18 and the fourth 32 electrons.
- In most atoms, the outer shells are never completely filled with electrons.
- The inner electrons travel fastest, the outer ones are the slowest.
Electrons move around an atom in paths
Properties of an Atom
Atomic Number
The atomic number tells you how many protons an atom has.
- For example, every hydrogen atom has the atomic number 1 because it only has 1 proton.
Elements that have atomic numbers of up to 92 can be found in nature; those over 92 are created by scientists in a laboratory.
The atomic number tells us where we can find an element in the periodic table. This table shows all the atoms in groups.
Atomic Mass
The atomic mass is the number of portions and neutrons in an atom. Although all atoms of the same element have the same number of protons, they sometimes have more neutrons. Such atoms are called isotopes. For example,
- hydrogen has three isotopes. Most of the time a hydrogen atom has one proton and one neutron. Sometimes you can find hydrogen isotopes that have two or three neutrons, but they too have only one proton.
In most lighter elements the nucleus of each atom has the same number of protons and neutrons. but heavier elements have more neutrons than protons.
Uranium , for example has 92 protons and 146 neutrons. It’s atomic mass is 238.
Uranium , for example has 92 protons and 146 neutrons. It’s atomic mass is 238.
The atomic mass is never a whole number, because scientists do not just add protons and neutrons together. They use a complicated formula.
The Periodic Table of Elements
Electric charge
Normally an atom is electrically neutral. But it can gain or lose electrons when it crashes with other atoms. Atoms that gain or lose electrons are called ions. They have an electric charge.
Atoms that lose electrons become positive ions; atoms that win electrons become negative ions.
Radioactivity
In some atoms the nucleus can change naturally. Such an atom is radioactive. When a nucleus changes it produces rays.
In nature, there are some elements that are radioactive, like uranium or radium. In labs scientists can produce radioactivity bybombarding atoms with smaller particles.
Atomic energy
In the 1930s and 40s scientists found out that if they bombarded a uranium atom with a neutron the nucleus would split up into two parts. When this happens energy is set free. We call this nuclear fission.
Fission was first used in atomic bombs that the Americans dropped over Japan to end the Second World War. The bombs released so much energy that they killed hundreds of thousands of people. Later on scientists found out how this energy could be used in a peacefulway.
In the 1950s the first atomic reactors were built. They produced energy by splitting atoms.
Compounds
Compounds are groups of two or more elements that are tied together. They are created when two different atoms share the same electron or when electrons travel from one atom to another.
Every compound has certain features and a chemical formula. Water, for example, is a compound that has two hydrogen atoms and one oxygen atom in it . Its chemical formula is H 2O. When sodium (Na)combines with chlorine (Cl) you get a compound called salt (NaCl). Carbon and hydrogen atoms form methane, or natural gas (CH 4).
Compounds can be divided into two groups:
- organic compounds always have carbon atoms in them. You can find them in all living creatures, in plants and in a lot of our food, for example sugar and fat.
- All other compounds are called inorganic compounds.
Compounds can be solids, liquids or gases. They may also turn into many different colors. Some compounds react very quickly, others don’t react at all.
WORDS TO KNOW:
- acid = a strong liquid that can burn holes in materials or damage your skin
- alloy = a metal that is made up of two or more metals mixed together
- amino acid =one of the substances that combine to form proteins
- artist = a person who paints or makes drawings
- bacteria = very small living things that can lead to illnesses
- billion = a number with 9 zeros
- boil = when a liquid becomes hot enough it turns into a gas
- bombard = to shoot at
- bond = two or more things become fixed together
- building block = the pieces or parts of an object
- carbon =a chemical substance that is in coal, oil or diamonds
- carbon dioxide =the gas that is produced when people or animals blow out air or when carbon is burned
- chain =line that is connected
- charge = electricity that is put into an electrical object, like a battery
- chlorine = a greenish yellow gas with a strong smell
- combine = to get together with
- common = you can find it very often
- complicated = not easy
- compound = is made up of two or more elements
- condense = if a gas becomes a liquid
- consist = are made up of
- copper = a reddish-brown metal used to make wires and pipes
- corrode = to rust
- create = make
- creature = anything that is living
- crown = a top for a bad tooth
- decorate = to make something look nice by putting objects on it
- diameter = a straight line from one side of a circle to the other
- drilling heads =the bottom part of a tool that you use to drill a hole into the earth to find oil or gas
- electrical charge =electricity that is put into an electrical object, like a battery
- engine =motor, a machine that produces power
- feature = characteristic, quality
- fertilizer = something that you put into the soil to make plants grow
- fission = when you split atoms to produce energy
- fuel = material like coal or oil that can be burned to make energy
- gain = to get one more of something
- graphite = a soft black material you can find in pencils
- haemoglobin = a red substance in your body that has iron in it and carries oxygen
- hydrocarbon = a compound made up of hydrogen and carbon
- hydrogen = a colourless gas that is the lightest of all elements
- in combination with =together with
- inhale = to breathe in something
- inorganic = everything that is not organic
- iron = a hard metal that is used to make steel
- isotope = different forms of an element
- jewellery = small things made of gold or silver that you wear
- lab = short word for laboratory
- laboratory = a special room in which scientists make experiments
- lead = a soft grey metal that melts very easily. It can be found in pencils.
- limestone = a kind of rock that has calcium in it
- liquid = something that is not solid or gas, like water
- lose = if you don’t have something anymore
- magnesium =a silver, white metal that burns with a bright white flame
- mass =the amount of material in something
- melt = if something changes from solid to liquid
- mine = to dig large holes in the ground to get raw materials
- mixture =combination, mix
- molecule =the smallest unit made up of two or more atoms
- naturally = by nature and not with the help of scientists
- nitrogen = a gas that has no smell or colour; it forms most of the Earth’s atmosphere
- noble gas = a pure gas that does not combine with other materials
- nucleus = the middle part of an atom with protons and neutrons
- occur =can be found
- orbit = to travel around an object in a circle
- ore = a rock that has metal in it
- organic = something that is living or is made by living things
- ounce =a unit for measuring weight = 28.35 grams
- outer = far away from the centre
- oxygen = a gas that is in our air and that we need to live
- particle = a very small piece of something
- periodic table = a list of elements that are in groups
- petrol = a liquid that comes from oil. It makes your car drive
- poisonous =a substance or material that can hurt or kill you
- polish = to make something bright and shiny
- pots and pans = steel objects that are used for cooking
- power =to make something run or work
- power plant = a building where electricity is produced
- pressure =the weight or power that you put on something
- pure = something that is not mixed with anything else
- radioactivity = if an atom sends out energy when the nucleus breaks apart
- ray = a line of light
- react = to change when mixed with something else
- reactor = a large machine that can produce nuclear energy
- rise = to go up
- rust =a reddish-brown substance that forms on iron or steel when it gets wet
- scientist =a person who is trained in science
- shape = the form that something has
- share =to have the same
- sheet =layer
- shell =path, layer
- sodium =a silver white metal that usually exists together with other chemicals , for example in salt
- solid =an object that is not a gas or a liquid
- split up = to divide into two or more parts
- structure = the ways things are connected to each other
- suffer from =to have pain
- surface =the top layer of an object
- tie = to hold together
- tin = a soft white metal that is often used to cover and protect steel
- uranium = a heavy white metal that is radioactive and used to produce nuclear power and bombs
- use =function, purpose
- weight = how heavy something is
- wire =thin metal that has the form of a thread; it is used to carry electricity or telephone signals
