Chemistry

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Atoms contain three sub-atomic particles called protons, neutrons and electrons. The protons and neutrons are found in the nucleus at the centre of the atom. The nucleus is very much smaller than the atom as a whole.
The number of electrons in an atom is always the same as the number of protons, so atoms are electrically neutral overall. if an atom loses one or more electrons, it becomes a positively charged ion.
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if an atom gains one or more electrons, it becomes a negatively charged ion. if an atom loses one or more electrons, it becomes a positively charged ion.
The number of protons in the nucleus of an atom is called its atomic number: the atoms of a particular element all have the same number of protons the atoms of different elements have different numbers of protons.
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The total number of protons and neutrons in an atom is called its mass number.
Isotopes are atoms of an element with the normal number of protons and electrons, but different numbers of neutrons. Isotopes have the same atomic number, but different mass numbers.Isotopes can either be radioactive or non-radioactive.
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Different atoms have different masses. Atoms have such a small mass it is more convenient to know their masses compared to each other. Carbon is taken as the standard atom and has a relative atomic mass (Ar) of 12.
The relative atomic mass of an element is a weighted average of the masses of the atoms of the isotopes - because if there is much more of one isotope then that will influence the average mass much more than the less abundant isotope will.
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There are more than 100 different elements. The periodic table is a chart showing all the elements arranged in order of increasing atomic number. The vertical columns in the periodic table are called groups.
Electrons are arranged in different shells around the nucleus. Each successive shell can only hold a certain number of electrons.
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Other cards in this set

Card 2

Front

The number of protons in the nucleus of an atom is called its atomic number: the atoms of a particular element all have the same number of protons the atoms of different elements have different numbers of protons.

Back

if an atom gains one or more electrons, it becomes a negatively charged ion. if an atom loses one or more electrons, it becomes a positively charged ion.

Card 3

Front

Isotopes are atoms of an element with the normal number of protons and electrons, but different numbers of neutrons. Isotopes have the same atomic number, but different mass numbers.Isotopes can either be radioactive or non-radioactive.

Back

Preview of the back of card 3

Card 4

Front

The relative atomic mass of an element is a weighted average of the masses of the atoms of the isotopes - because if there is much more of one isotope then that will influence the average mass much more than the less abundant isotope will.

Back

Preview of the back of card 4

Card 5

Front

Electrons are arranged in different shells around the nucleus. Each successive shell can only hold a certain number of electrons.

Back

Preview of the back of card 5

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