YEAR 10 SCIENCE, CHEMISTRY NOTES
ATOMS
- Everything is made up of atoms
Atoms are made up of a nucleus, electron cloud, and 3 subatomic particles: protons,
electrons, and neutrons.
- Protons are found in the nucleus of an atom, and are positively charged
- Electrons exist in the electron cloud. They move around and are negatively charged.
- Neutrons are found in the nucleus of an atom and have no charge.
ELECTRON ARRANGEMENT
- Electrons have different energy levels called shells.
- The first shell can only hold 2 electrons, but from there on they can hold 8 electrons.
- The outermost shell is called the valence shell. Electrons found in the valence shell
are called valence electrons.
- They are drawn by placing points (electrons) on circles (shells) around the element.
- They are written by first writing the number electrons in the first shell, then after a
comma, the numbers in the second shell, third shell and so on.
Eg; Oxygen= 2,6
ELEMENTS
- A pure substance (only containing one particle) made up of atoms, eg; lithium,
magnesium. These elements also have symbols, eg; L, Mg.
- A compound is also a pure substance made up of two or more elements combined.
You can tell if the formula contains more than one capital letter.
- Atomic number; the number of protons. It will be the smaller number
- Mass number; the number of protons + neutrons. It will be the bigger number
12
- E.g: 6 C (6 is the atomic number, 12 is the mass number.)
IONS
- When atoms lose or gain electrons to get a full outer shell. Full valence shells =
stability.
- Eg; The valence shell of oxygen holds 6 electrons, to make it full we must add 2
electrons (because the shells can hold 8) we add 2 because it’s easier to add 2 than
to lose 6. (If there is only one shell, a full valence can be 2.)
But then the symbol of oxygen cannot be O anymore because it became an ion. To
change it we must change the name and add on to the symbol. It becomes Oxide
and O ⁻².
It becomes O⁻² because now it has 2 extra electrons which are negative so the
protons and electrons aren’t balanced.
PROTONS 8 IN TOTAL
ELECTRONS 10 IN TOTAL, So there are 2 more negative.
ATOMS
- Everything is made up of atoms
Atoms are made up of a nucleus, electron cloud, and 3 subatomic particles: protons,
electrons, and neutrons.
- Protons are found in the nucleus of an atom, and are positively charged
- Electrons exist in the electron cloud. They move around and are negatively charged.
- Neutrons are found in the nucleus of an atom and have no charge.
ELECTRON ARRANGEMENT
- Electrons have different energy levels called shells.
- The first shell can only hold 2 electrons, but from there on they can hold 8 electrons.
- The outermost shell is called the valence shell. Electrons found in the valence shell
are called valence electrons.
- They are drawn by placing points (electrons) on circles (shells) around the element.
- They are written by first writing the number electrons in the first shell, then after a
comma, the numbers in the second shell, third shell and so on.
Eg; Oxygen= 2,6
ELEMENTS
- A pure substance (only containing one particle) made up of atoms, eg; lithium,
magnesium. These elements also have symbols, eg; L, Mg.
- A compound is also a pure substance made up of two or more elements combined.
You can tell if the formula contains more than one capital letter.
- Atomic number; the number of protons. It will be the smaller number
- Mass number; the number of protons + neutrons. It will be the bigger number
12
- E.g: 6 C (6 is the atomic number, 12 is the mass number.)
IONS
- When atoms lose or gain electrons to get a full outer shell. Full valence shells =
stability.
- Eg; The valence shell of oxygen holds 6 electrons, to make it full we must add 2
electrons (because the shells can hold 8) we add 2 because it’s easier to add 2 than
to lose 6. (If there is only one shell, a full valence can be 2.)
But then the symbol of oxygen cannot be O anymore because it became an ion. To
change it we must change the name and add on to the symbol. It becomes Oxide
and O ⁻².
It becomes O⁻² because now it has 2 extra electrons which are negative so the
protons and electrons aren’t balanced.
PROTONS 8 IN TOTAL
ELECTRONS 10 IN TOTAL, So there are 2 more negative.
