Document page
chemistry igcse acapprinted 10 · PDF 10
145 pagesrevision 46934
printed 10 · PDF 10
Page image rendered from the stored file at 110 dpi; it sharpens as you zoom. Outlines are placed from each region’s stored position on the page (612 × 792 pt).
readable
Source of this text: embedded text layer. The better of the embedded text and OCR is kept.
10
• An atom is the smallest particle of an element, while two or more atoms that are bonded together form a
molecule.
• An element is a pure substance that cannot be broken down any further and is made up of only one type of
atom. e.g. Nitrogen (N2), Carbon (C).
• A mixture is when two or more elements are physically joined together, e.g. soil, cement and can be
separated via physical means, for e.g distillation, evaporation, filtration .
• A compound is when two or more elements are chemically joined together, e.g. Sodium chloride (NaCl),
Water (H2O).
The subatomic particles inside an atom
• Inside every atom exist three types of subatomic particles:
1. Protons
2. Neutrons
3. Electrons
• Protons:
Protons (along with Neutrons) are found inside the nucleus of an atom. One proton has a relative mass of 1,
and a positive charge of +1.
Each atom has the same number of protons as it does electrons.
• Neutrons:
Neutrons (along with Protons) are found inside the nucleus of an atom. One neutron has a relative mass of
1, and a neutral charge of 0.
• Electrons:
Electrons can be found orbiting the nucleus of an atom in electron shells. One electron has a relative mass of
1/1840 where 1 is the mass of a proton/neutron, and a negative charge of -1.
Each atom has the same number of electrons as it does protons.
Each electron shell has a specific capacity of electrons it can hold. The first electron shell can only hold 2
electrons, while the rest can hold 8. e.g. a sodium atom () has 2 electrons in its first shell, 8 electrons in its
second shell, and 1 electron in its first shell, giving it an electronic configuration of 2,8,1.
When the first electron shell is full , it is known as a duplet (2)
When any other electron shell is full , it is known as an octet (8)
The Electronic configuration of an element is written like this :