Gap-fill worksheet question Quiz "Atomic Structure"

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atom06.gif 1a. Atoms are made of fundamental particles called (+), (0) and (-).
1b. The mass of proton is , the mass of a neutron is and the mass of an electron is ~.
1c. The centre of the atom is called the .
1d. It consists of and neutrons and contains most of the mass of the atom.

2a. The number of protons in the atom is called the . It also equals the number of in a neutral atom.
2b. The is the sum of the protons and neutrons in the nucleus.

3. An atom of mass number 43, and atomic number 21, consists of protons, neutrons and electrons.

iron_56.gif 4a. The is defined as the sum of the protons plus neutrons in the .
4b. In the symbol for an atom of shown on the left, the atom consists of protons, neutrons and electrons.
4c. Atoms of the same element with a different due to different numbers of neutrons are called .

5a. Image90.gifImage422.gif Both of these atoms of have protons and electrons, but the left atom has neutrons and the right atom has neutrons.
5b. The of an element is defined as the of all the atoms present in an element compared to the mass of a carbon-12 atom (designated 12.000 atomic mass units).