today we will learn the basics of chemistry in life science
Atoms, Elements, and the periodic table
Metals, semimetals (metalloids), and nonmetals.
Further grouping: transition metals, rare earths, alkali metals, alkaline earth, halogens, and noble gasses.
An element is a pure substance that is made up entirely of one type of atom.
reading atomic symbols
The atom is the basic unit of matter.
Atoms are made up of protons, neutrons, and electrons.
Protons and Neutrons are particles that are bound together by strong atomic forces and for the center of the atom, we call it the nucleus.
Protons have a positive charge
Neutrons carry no charge
Protons and electrons have around the same mass.
Electrons are negatively charged, they are 1/1840 of the mass of a proton.
Electrons in constant motion around the nucleus of the atom.
Electron are arranged in a series of orbits called shells:
The shells can only hold a certain number of electrons.
The first shell can hold two electrons.
The second shell can hold up to eight electrons.
Atoms have an equal number of protons and electrons, so all atoms are electrically neutral because the positive charge f the protons and the negative charge of the electrons cancel out.
Are atoms of the same element that contain different number of neutrons. They have a different mass.
Sometimes atoms gain or lose electrons. The atom then loses or gains a "negative" charge. These atoms are then called ions.
Positive Ion - Occurs when an atom loses an electron (negative charge) it has more protons than electrons.
Negative Ion - Occurs when an atom gains an electron (negative charge) it will have more electrons than protons.
The following image shows Na losing an electron and Cl gaining an electron
Thus the Na becomes Na+
The Cl becomes Cl-
Form when atoms transfer electrons between each other, forming ions that are electrically attracted to each other forming a bond between them. Sodium chloride (NaCl) is a typical ionic compound.
A polar bond is a covalent bond between two atoms where the electrons forming the bond are unequally distributed. This causes the molecule to have a slight electrical dipole moment where one end is slightly positive and the other is slightly negative.
A covalent bond, also called a molecular bond, is a chemical bond that involves the sharing of electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs, and the stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding.
Atoms can share between two and six electrons.
Van der Waals FOrces
Dipole: a pair of equal and oppositely charged or magnetized poles separated by a distance.
Author: Jazmin Gannon
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