Atoms
Atoms contain protons, neutrons and electrons
Atoms have a radius of about 10 nanometres(1x10(-9)). There are a few different modern models of the atom.
The nucleus
It’s in the middle of the atom
It contains protons and neutrons
The nucleus has a radius of around 1x10(-14) which is around 1/10,000 the radius of an atom
It has a positive charge because of the protons
Almost the whole mass of the atom is concentrated in the nucleus
The electrons
Move around the nucleus in electron shells
They’re negatively charges and tiny, but they cover a lot of space
Electrons have virtually no mass
Particles, relative mass and charge
Proton:1 and +1
Neutron:1 and 0
Electron:Very small and -1
Number of protons equals number of electrons
Atoms are neutral-they have no charge overall(unlike ions).
This is because they have the same number of protons as electrons
The charge on the electrons is the same size as the charge on the protons, but opposite-so the charges cancel out
In an ion, the number of protons doesn’t equal the number of electrons. This means it has an overall charge. For example, an ion with a 2- charge, has two more electrons than protons
Atomic Numbers and Mass Number describe an Atom
The nuclear symbol of an atom tells you its atomic(proton) number and mass number
The atomic number tells you how many protons there are
The mass number tells you the total number of protons and neutrons in the atom
To get the number of neutrons, just subtract the atomic number from the mass number
Atoms
Atoms contain protons, neutrons and electrons
Atoms have a radius of about 10 nanometres(1x10(-9)). There are a few different modern models of the atom.
The nucleus
It’s in the middle of the atom
It contains protons and neutrons
The nucleus has a radius of around 1x10(-14) which is around 1/10,000 the radius of an atom
It has a positive charge because of the protons
Almost the whole mass of the atom is concentrated in the nucleus
The electrons
Move around the nucleus in electron shells
They’re negatively charges and tiny, but they cover a lot of space
Electrons have virtually no mass
Particles, relative mass and charge
Proton:1 and +1
Neutron:1 and 0
Electron:Very small and -1
Number of protons equals number of electrons
Atoms are neutral-they have no charge overall(unlike ions).
This is because they have the same number of protons as electrons
The charge on the electrons is the same size as the charge on the protons, but opposite-so the charges cancel out
In an ion, the number of protons doesn’t equal the number of electrons. This means it has an overall charge. For example, an ion with a 2- charge, has two more electrons than protons
Atomic Numbers and Mass Number describe an Atom
The nuclear symbol of an atom tells you its atomic(proton) number and mass number
The atomic number tells you how many protons there are
The mass number tells you the total number of protons and neutrons in the atom
To get the number of neutrons, just subtract the atomic number from the mass number