C1.1
- Created by: mel
- Created on: 21-05-13 17:27
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- C1.1
- Fundemental ideas
- Atoms, elements and compounds.
- Everything is made out of atoms.
- Elements contain only one type of atom.
- Compounds contain more than one type of atom.
- An atom has a tiny nucleus in its centre, surrounded by electrons.
- Agrouping of two or more atoms bonded together is called a molecule.
- Chemical bonds hold the hydrogen and oygen atoms together in water molecule. Water is an example of a compound.
- There are about 100 different elements.
- Elements are shown in the periodic table.
- Atomic structure
- Atoms are made of protons, neutrons and electrons
- Protons and neutrons are inside of the atoms nucleus.
- Electrons are outside of the nucleus, on energy levels.
- Protons and electrons have equal and opposite charges.
- Protons had a positive charge and electrons have a negative charge.
- Neutrons have no electrical charge. They are neutral.
- Atomic number= number of protons/ electrons.
- Mass number= number of protons + neutrons.
- Atoms are arranged in the periodic table in order of their atomic number.
- Atoms are made of protons, neutrons and electrons
- The arrangement of electrons in atoms
- The electrons in an atom are arranged in energy levels or shells.
- Atoms with the same number of electrons in their outermost shell belong in the same group of the periodic table.
- The number of electrons in the outermost shell of an element's atoms determines the way that element reacts.
- The atoms of the unreactive noble gases(in group 0) all have very stable arrangements of electrons
- There is a maximum amount of electrons you are allowed on energy levels.
- On the second and third energy levels you are allowed a maximum of 8 electrons, per energy level.
- On the fourth energy level you are allowed a maximum of 18 electrons.
- On the first energy level you are only allowed 2 electrons
- Forming bonds
- Sometimes atoms react together by transferring electrons to form chemical bonds.
- This happens when metals react with non metals.
- If the reacting atoms are all non-metals, then the atoms share electrons to form chemical bonds.
- When metals react with no-metals, charged particles called ions are formed.
- This happens when metals react with non metals.
- When atoms from different elements react together they make compounds.
- The formula of a compound shows the number and type of atoms that have bonded together to make that compound.
- Chemical reactions
- When elements react, their atoms join with other atoms to form compounds. There are two types of joining.
- Ionic bonding
- Compounds formed from metals and non metals.
- Metals lose electrons to form positive ions.
- Compounds formed from metals and non metals.
- Covalent bonding
- Compounds formed from non-metals consist of molecules,
- The electrons are shared.
- Compounds formed from non-metals consist of molecules,
- Ionic bonding
- When elements react, their atoms join with other atoms to form compounds. There are two types of joining.
- Sometimes atoms react together by transferring electrons to form chemical bonds.
- Atoms, elements and compounds.
- Fundemental ideas
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