Electrons In an electrically neutral atom, positive charges of protons are balanced by the negative charges of electrons. Orbital is the volume of spa

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Outline Basic Chemistry Chapter 2 Chemical Elements Atoms Isotopes Molecules and Compounds Chemical Bonding Ionic and Covalent Acids and Bases Chemical Elements Matter refers to anything that has

1 Outline Basic Chemistry Chapter 2 Chemical Elements Atoms Isotopes Molecules and Compounds Chemical Bonding Ionic and Covalent Acids and Bases Chemical Elements Matter refers to anything that has mass and takes up space. 92 naturally occurring elements. Only six make up 98% body weight of organisms. CHNOPS Carbon Nitrogen Oxygen Phosphorus Sulfer Atoms Atoms are the smallest unit of matter. Atomic symbol represents each element. Protons and neutrons found in nucleus. Electrons orbit nucleus. Mass number equals sum of protons and neutrons. Atomic number refers to number of protons. Periodic Table Elements grouped in periodic table based on individual characteristics. Vertical columns are groups. Horizontal o rows are periods. Isotopes Isotopes are atoms of the same element with a differing number of neutrons. Therefore some atoms of the same element will weigh different amounts. H 1 no neutron H 2 1 neutron Total population determines weight H= thus most H is H 1

2 Electrons In an electrically neutral atom, positive charges of protons are balanced by the negative charges of electrons. Orbital is the volume of space where an electron is most likely to be found. Electrons are attracted to the nucleus, and thus energy is required to push electrons into higher orbits. Electron Orbitals Electron orbitals are the position of the electron in relation to the energy that it uses. We will look at s and p orbitals S orbitals hold 2 electrons P orbitals hold 6 electrons H =1 s 1 He=1s 2 This element has a full shell and is happy Notice all elements in column 18 are happy Orbitals Li=1s 2 2s 1 Be=1s 2 2s 2 B= 1s 2 2s 2 2p 1 C=1s 2 2s 2 2p 2 N=1s 2 2s 2 2p 3 O=1s 2 2s 2 2p 4 F=1s 2 2s 2 2p 5 Ne=1s 2 2s 2 2p 6 Notice the pattern? Total the superscripts ad you get the atomic number Elements and Compounds Molecule - Two or more atoms bonded together. Compound - Two or more different types of atoms bonded together. Ionic Bonding Ionic bonds are formed when electrons are stolen from one atom to another. Electron transfer causes a charge imbalance in each atom. Ions Sodium Chloride Sodium Chloride Na=1s 2 2s 2 2p 6 3s 1 Na + = 1s 2 2s 2 2p 6 Missing an electron thus + charged Cl = 1s 2 2s 2 2p 6 3s 2 3p 5 Cl-=1s 2 2s 2 2p 6 3s3p 6 Gained an electron thus charged These combine to form a matrix due to charges Table salt

Covalent Bonding Covalently Bonded Molecules Covalent bonds are formed when two atoms share electrons so that each atom has a complete outer shell.

3 Covalent Bonding Covalently Bonded Molecules Covalent bonds are formed when two atoms share electrons so that each atom has a complete outer shell. Molecule Shapes Molecules have three-dimensional shapes. Models Ball and stick Space-filling Covalent Bonding Nonpolar covalent bonds are formed when sharing of electrons between atoms is equal. Polar covalent bonds are formed due to unequal sharing of electrons between atoms. Electronegativity Electronegativity is the attraction of an atom for the electrons in a covalent bond Most electronegative is F Hydrogen Bonding A hydrogen bond is formed when polarity within a water molecule causes the hydrogen atoms in one molecule to be attracted to the oxygen atoms in the other water molecules. Weak and easily broken. Many together can be quite strong. Charge gradient On one extreme is stealing on the other is sharing or On one extreme is ionic on the other is covalent bonding H bonding is in the middle Ionic Polar H Nonpolar true covalent Electronegativity

4 Water Molecule High Heat Capacity Large number of hydrogen bonds absorb heat without a large change in temperature. High Heat of Vaporization Large number of hydrogen bonds must be broken to evaporate water. Solvent Hydrophilic - Attracts water. Hydrophobic - Cannotattractwater. attract A solution contains dissolved solutes. Cohesive and Adhesive Water can be drawn up a tubular vessel. High Surface Tension Frozen water less dense than liquid water. Ice acts as an insulator on top of a frozen body of water. Melting ice draws heat from the environment. Acids and Bases Acids are substances that dissociate in water and release hydrogen ions (H + ). Bases are substances that either take up hydrogen ions (H + ) or release hydroxide ions (OH - ). ph Scale ph scale used to indicate acidity and basicity of a solution. Ranges from = Neutral >7 = Base <7 = Acid Logarithmic Scale

hydroxide Review Chemical Elements Atoms Isotopes Molecules

5 H + + Cl- HCl acid since H + K + + OH - KOH Acid or Base base since OH- Na + + Cl- Na + Cl- Salt since no hydronium nor hydroxide Review Chemical Elements Atoms Isotopes Molecules and Compounds Chemical Bonding Ionic and Covalent Acids and Bases

Learning Objectives. Learning Objectives (cont.) Chapter 2: Basic Chemistry 1. Lectures by Tariq Alalwan, Ph.D.

Learning Objectives. Learning Objectives (cont.) Chapter 2: Basic Chemistry 1. Lectures by Tariq Alalwan, Ph.D. Biology, 10e Mader Lectures by Tariq Alalwan, Ph.D. Learning Objectives Name the principal chemical elements in living things. Compare the physical properties (mass and charge) and locations of electrons,