Chapter 2 part 1: Basic Chemistry

What is Chemistry? Chemistry is sometimes called the central science, as its principles are central to understanding all aspects of science, including biology and physiology. Pharmacology is the science of drugs, including their composition, uses, and effects on the body. Drugs are chemical compounds that have specific effects on the body’s mechanisms.

Matter and Energy Matter—anything that occupies space and has mass (weight) Energy—the ability to do work Chemical Electrical Mechanical Radiant

Composition of Matter Elements—fundamental units of matter Atom-is the smallest unit of an element that retains its chemical properties. Every pure element is composed of only one kind of atom. For example carbon is composed of only carbon atoms.

Chemical Composition of the Body CHEMICAL ELEMENTS % BODY COMPOSITION Carbon (C) Nitrogen (N) 96% Oxygen (O) Hydrogen (H) Calcium (Ca) Phosphorus (P) 3% Potassium (K) Sulfur (S) Iron (Fe) Chlorine (Cl) Trace quantities Iodine (I) Sodium (Na) Magnesium (Mg) Copper (Cu) Manganese (Mn) Cobalt (Co) Zinc (Zn) Chromium (Cr) Fluorine (F) Molybdenum (Mo) Silicon (Si) Tin (Sn)

Atomic Structure Every atom is composed of three different particles. 1) Protons- which are positively charged particles, located inside the nucleus of the atom. 2) Neutrons- which is a particle with no charge. Also located inside the nucleus. Because there is no negative charges inside the nucleus to counter act the positively charged protons, the overall charge of the nucleus is positive. 3) Electrons- These are particles that have a negative charge and are found outside the nucleus.

Atomic Structure of Smallest Atoms

Identifying Elements Atomic number—equal to the number of protons that the atom contains Atomic mass number—sum of the protons and neutrons Chemical symbol- A 1,2 or 3 letter abbreviation used to represent different elements. Atomic # Chemical Symbol Atomic mass #

Isotopes and Atomic Weight Have the same number of protons Vary in number of neutrons

Radioactivity Radioisotope Heavy isotope Tends to be unstable Decomposes to more stable isotope Radioactivity—process of spontaneous atomic decay. Isotopes have important medical uses. Radioisotopes are frequently used by radiologists and oncologists to diagnose and treat diseases.

Molecules and Compounds Molecule—two or more like atoms combined chemically Compound—two or more different atoms combined chemically Figure 2.4

Chemical Bonding Atoms are united by chemical bonds Atoms dissociate from other atoms when chemical bonds are broken

Electrons and Bonding Electrons occupy energy levels called electron shells Electrons closest to the nucleus are most strongly attracted Each shell has distinct properties The number of electrons has an upper limit Shells closest to the nucleus fill first

Electrons and Bonding Bonding involves interactions between electrons in the outer shell (valence shell) Full valence shells do not form bonds

Inert Elements Atoms are stable (inert) when the outermost shell is complete How to fill the atom’s shells Shell 1 can hold a maximum of 2 electrons Shell 2 can hold a maximum of 8 electrons

Inert Elements Atoms will gain, lose, or share electrons to complete their outermost orbitals and reach a stable state Rule of eights Atoms are considered stable when their outermost orbital has 8 electrons The exception to this rule of eights is Shell 1, which can only hold 2 electrons

Inert Elements Figure 2.5a

Reactive Elements Valence shells are not full and are unstable Tend to gain, lose, or share electrons Allow for bond formation, which produces stable valence

Chemical Bonds Ionic bonds Ions Form when electrons are completely transferred from one atom to another Ions Charged particles Anions are negative (gain e) Cations are positive (lose e)

Ionic Bonds + – Na Cl Na Cl Sodium atom (Na) (11p+; 12n0; 11e–) Chlorine atom (Cl) (17p+; 18n0; 17e–) Sodium ion (Na+) Chloride ion (Cl–) Sodium chloride (NaCl)

Ionic Bonds Na Cl Sodium atom (Na) (11p+; 12n0; 11e–) Chlorine atom (Cl) (17p+; 18n0; 17e–)

Ionic Bonds Na Cl Sodium atom (Na) (11p+; 12n0; 11e–) Chlorine atom (Cl) (17p+; 18n0; 17e–)

Ionic Bonds + – Na Cl Na Cl Sodium atom (Na) (11p+; 12n0; 11e–) Chlorine atom (Cl) (17p+; 18n0; 17e–) Sodium ion (Na+) Chloride ion (Cl–) Sodium chloride (NaCl)

Chemical Bonds Covalent bonds Atoms become stable through shared electrons Single covalent bonds share one pair of electrons Double covalent bonds share two pairs of electrons

Examples of Covalent Bonds

Examples of Covalent Bonds

Polarity Covalently bonded molecules Some are non-polar Some are polar Electrically neutral as a molecule Some are polar Have a positive and negative side

Chemical Bonds Hydrogen bonds Weak chemical bonds Hydrogen is attracted to the negative portion of polar molecule Provides attraction between molecules

Patterns of Chemical Reactions Synthesis reaction (A + BAB) Atoms or molecules combine Energy is absorbed for bond formation Decomposition reaction (ABA + B) Molecule is broken down Chemical energy is released

Synthesis and Decomposition Reactions Figure 2.10a

Synthesis and Decomposition Reactions Figure 2.10b