Page 349 - General Knowledge

GENERAL KNOWLEDGE 2019

Vander Woals Interactions
 Attractions between ever changing + and – ―hot spots‖ in covalently bonded nonpolar
molecules.
 Individual bonds are weak and temporary, but collectively they are strong and play important
biological roles.

2. ATOMIC STRUCTURE
Atom
 The smallest particle of an element that still retains the chemical properties of that element.
 Atoms are composed of 3 sub-atomic particles.
 Electrons: Electrons are the smallest of the three particles that make up atoms.
 Electrons possess negative electrical charges.
 Travel around the nucleus in orbitals or shells.
 The first shell – K shell – holds 2 electrons then it is full.
 The second shell – L shell – holds 8 electrons until full.

 The third shell – M shell – holds 8 electrons until full.
 The fourth shell – N shell – holds 18 electrons until full.
 The fifth shell – O shell – holds 18 electrons until full.
 The sixth shell – P shell – holds 32 electrons until full.
 The seventh shell – Q shell 0 holds 32 electrons until full.
 Electrons are found in shells or orbitals that surround the nucleus of an atom.
 Protons: Protons possess a positive electrical charge.
 Protons are found clumped together within the nucleus of an atom.
 Each proton has a mass of 1 AMU or 1 Dalton.
 Neutrons: Neutrons possess no electrically charged and are therefore referred to as neutral.

 Neutrons are also found clumped together within the nucleus of an atom.
 Each neutron has a mass of 1 AMU or 1 Dalton.
Nuclear Forces
 These are short-range proton to neutron or proton to proton or neutron to neutron attractive
forces that help together the nucleus of an atom.
 These forces are greater than the repulsive, same charge electrical forces exhibited by
protons.
Atomic Radii
 This term refers to the relative size of an individual atom of an element.
 It is measured from the center of the nucleus to the outermost electron cloud.
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 It is measured in picometers. A picometer is 1.0 × 10 meters.
Dalton‘s Atomic Theory (1808)
 All matter is made up of atoms.
 Atoms are indivisible (cannot be broken down into smaller pieces).
 All atoms of a given element are exactly alike in size, mass and shape.
 Atoms of different elements can combine in simple whole number ratios to form compounds.
 Atoms are simply just rearranged in chemical reactions.
Law of Definite Proportions
 Atoms combine in simple whole number ratios to form compounds.
Law of Multiple Proportions

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