The Chemistry of Life Chapter 2: Covers Section 2-1, and 2-2

Atoms (page 35 in Biology Book) The basic unit of matter is called a(n) ATOM Strong bonds from the protons and neutrons bind the nucleus together in a atom

Subatomic Particles ParticleChargeLocation in Atom ProtonPositive (+)Inside nucleus NeutronNeutral (No charge) Inside Nucleus ElectronNegative (-)Space surrounding nucleus

Why are atoms neutral despite having charged particles? There are equal protons and electrons, thus they are neutral …

Elements and Isotopes(page 36) What is a chemical element? – Pure substance that consists entirely of one type of atom. What does an elements atomic number represent? – Number of protons in the element Atoms of the same element that differ in the number of neutrons they contain are known as ISOTOPES How are isotopes identified? – Identified by mass number Why do isotopes of an element have the same chemical properties? – Same number of Electrons

Chemical compounds (page 37) What is a chemical compound? – Formed by the chemical combination of two or more elements in definite proportions. Two elements can be completely different and combine to form a completely different compound. (Example: Table Salt, combination of Sodium, and chlorine)

Chemical Bonds (Page 38-39) Chemical bonds hold atoms in compounds together.

Chemical Bonds TypeFormed when … Covalent BondFormed when electron are shared between atoms Iconic bondFormed when one or more electrons are transferred from one atom to another.

What is a ion? – Positively, and negatively charged atoms Atoms that lose electrons become positive, because the number of protons and electrons becomes unbalanced, and the number of protons (+), makes the atom positive. The structure that results when atoms are joined together by covalent bonds is called a(an) MOLECULE Facts: – Atoms share six electrons, and can form a triple bond – In a covalent bond, atoms share electrons The slight attractions that develop between oppositely charged regions of nearby molecules are called VANDER WAALS FORCES

Properties of Water (Page 40-43) The Water Molecule – True/False? A water molecule is neutral. FALSE A water molecule is considered polar because the hydrogen atoms are slightly positive, and the oxygen is slightly negative. – True facts about Hydrogen Bonds The attractions between the hydrogen atom on one water molecule and the oxygen atom on another water molecule is an example. They are the strongest bonds that form between molecules.

Forms of Attraction Form of Attractiondefinition CohesionIs a attraction between molecules of the same substance AdhesionAttractions between molecules of different substances.

Why is water extremely cohesive? That is a result of hydrogen bonding. The rise in water in a narrow tube against the force of gravity is called ADHESION The capillary action affects plants by allowing water to be pulled from roots, into the stem, and leaves of a plant.

Solutions and Suspensions (Pg ) What is a Mixture? A mixture is a material composed of two or more elements or compounds that are physically mixed together, but not chemically combined. A mixture of two or more substances in which the molecules of the substances are even evenly mixed is called a(an) SOLUTION The greatest solvent in the world is WATER (H 2 O) What is a suspension? Mixtures of water of water and non dissolved materials.

SUBSTANCES IN SOLUTIONS SUBSTANCEDEFINITIONSALTWATER SOLUTION SoluteSubstance that is dissolved SALT SolventSubstance in which the solution dissolves WATER

Acids, bases, and pH (Pg ) Two water molecules can react to form IONS Water is neutral is because there are a equal number of positive hydrogen ions, and negative hydroxide ions produced. What does the pH scale indicate? – To indicate ions in a solution

pH Scale Example

Continued … On the pH scale, substances that have a pH below 7 are considered acids. Examples of acid would be, stomach acid, hydrochloric acid, and lemon juice. Substances that have a pH over 7, are called bases. Examples of bases, would be, sea water, soap, bleach, and Lye. Substances with a pH of 7 are neutral. Ex. Would be pure water. When people taste acids and bases, acids are sour, while bases are bitter.

Continued … Buffers – Weak acids or bases that can react with strong acids, or bases, to prevent sharp sudden changes in pH.

Powerpoint created by Nick Franga