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CHE 12 Bonding review. Particles in Chemistry. Particles in Chemistry. Atoms (very tiny: trillions of atoms in a speck of dust) Ions (also very tiny: approximately atomic-sized)
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CHE 12 Bonding review Particles in Chemistry
Particles in Chemistry • Atoms (very tiny: trillions of atoms in a speck of dust) • Ions (also very tiny: approximately atomic-sized) • Molecules (most are larger than atoms, but are tiny as well: For one molecule to be the size of a dust particle, it would have to be made of over a trillion atoms)
Other “Chemistry” Particles • Three main Subatomic Particles • These subatomic particles make up each of the more than 3100 known different atoms. • Each of these different atoms is called a nuclide. • There are about 340 naturally-occurring nuclides on Earth.
Atomic Number • Each different nuclide is unique. This is due to a distinctive combination of its subatomic particles. • In all these nuclides, the number of protons ranges from 1 to 118. • Different nuclides with the same number of protons are called isotopes of a given element. • The number of protons in each of these isotopes is the Atomic Number of that element.
Isotopes • Atoms of isotopes (when neutral) all have the same number of electrons as well. It is the number of neutrons which varies from one isotope to another. • For example: C-12, C-13, C-14
ddd • Each of these three carbon atoms would have a different mass. • Fortunately, naturally-occurring samples of an element have a fixed ratio of isotopes (by count). We use the “weighted” average method to determine the average relative atomic mass. (see “Isotopes and Atomic Mass” page 43 in your textbook.)
Physical and Chemical Properties • If you were to separate the isotopes of an element, you would likely be able to detect different physical characteristics such as density, melting and boiling points. • However, they would all behave the same way chemically. • This is because the chemical properties depend primarily on the electron cloud arrangement which is identical for all the isotopes of the element.
Chemical Properties • Thus in chemistry, we rarely need to think about the individual isotopes in a sample. • Since they all react the same way, we usually just use the concept of an “average atom”.
Bonding Almost all substances consist of atoms or ions that are bonded to each other. (Exceptions to this are the Noble Gases.) The particles of a Nobel gas are single, unbonded atoms. This means that of the millions of substances , there are only six of those substances that consist of unbonded atoms!!!
Bonding • Bonding in chemistry is always the result of some positively-charged particle(s) attracting some negatively-charged particle(s). • There are several types of bonding (done in grade 11): • Covalent • Ionic • Metallic • Van der Waal’s Forces Unit 2 Page 156-233 in your textbook.