Atoms consist of a nucleus containing protons and neutrons, surrounded by electrons in shells. The numbers of particles in an atom can be calculated from its atomic number and mass number.
Which of Dalton's ideas about atoms is no longer thought to be true?
All matter is made of tiny particles called atoms
The atoms of different elements are different from one another
Atoms cannot be broken down into anything simpler
What did the Geiger-Marsden experiment show?
Atoms consist of a sphere of positive charge with electrons dotted around inside
Atoms consist of a relatively small, positively charged nucleus surrounded by electrons
Electrons are arranged in shells or energy levels
Which particles are found in the nucleus of most atoms?
Protons and electrons
Protons and neutrons
Neutrons and electrons
Which of these subatomic particles has the least mass?
Why are most atoms neutral?
Because they contain no charged particles
Because they have equal numbers of protons and electrons
Because they have more neutrons than protons
How many protons, electrons and neutrons are in an atom which has an atomic number of 11 and a mass number of 23?
11 protons, 11 electrons, 12 neutrons
11 protons, 11 electrons, 23 neutrons
11 protons, 12 electrons, 11 neutrons
Which of these describes isotopes of an element?
Atoms with the same number of protons and electrons but different numbers of neutrons.
Atoms with the same number of protons and neutrons but different numbers of electrons.
Atoms with the same number of neutrons and electrons but different numbers of protons.
Which of these pairs of atoms are isotopes of the same element?
Atom A: atomic number 12, mass number 24, Atom B: atomic number 11, mass number 24
Atom A: atomic number 11, mass number 24, Atom B: atomic number 11, mass number 24
Atom A: atomic number 12, mass number 24, Atom B: atomic number 12, mass number 25
What is the name for charged particles formed when atoms lose or gain electrons?
An aluminium ion, Al3+, contains 13 protons. How many electrons does an aluminium ion contain?