CHEMISTRY – chapters 5,6,7
1. Physical Properties: can be observed without changing the composition. i.e colour, density, taste, smell, boiling point. Chemical Properties: cannot be observed without changing the composition i.e combustability, corrosiveness Qualitative Properties: word descriptions Quantitative: numerical mesurements. Signs of chemical reaction: 1. colour change 2. new gas (bubbling or new smell) 3. new shape 4. releases heat or light 5. precipitate forms (solid)
4. Periods: Horizontal rows (7) Groups: vertical columns (18) elements in the first period have one shell, second period= 2 shells, etc. Metals: solid, shiny, malleable, good conductors (nickle ni) Nonmetals: can be solid, liquid or gas
Families: Noble Gases: very stable and unreactive. Do not ordinarily form compounds. Halogens: reactive nonmetals. React with metals to form salt (table salt NaCl) Alkali Metals: Extremely reactive with water and air Alkaline Earth Metals: Commonly react with oxygen to form oxide compounds
5.5 Ions: Atoms that have gained or lost electrons are called ions
Electrons in the valence shell are gained or lost to become more stable Cations: Positively charged ions (Electrons < Protons) Anions: Negatively charged ions (Electrons > Protons) Protons: Are not gained or lost in normal chemical reactions Neutrons: Found in every nucleus except Hydrogen, are not gained or lost in normal chemical reactions, Help stabilize nucleus Electrons: Get transferred or shared between atoms in normal chemical reactions, Move around nucleus in nearly circular paths called orbits
* Number of protons = atomic number / Number of neutrons = mass-atomic number / protons plus charge = electrons
5.11 Ionic Compounds: metals are named normally, and nonmetals are named ending in “ide”. i.e magnesium chloride Molecular compounds: prefixes are used. 1- mono 2-di 3-tri 4-tetra 5-penta 6-hexa 7-hepta 8-octa 9-nona 10-deca
Covalent bonding (molecular): H 2 O
Ionic Bonding (ionic): NaCl
5.10 diatomic elements: a molecule consisting of only two atoms of either the same or different elements.
I (I2) Brought(Br2) Cleaner (Cl2) For (F2) Our (O2) New(N2) House (H2) Paid For (P4) By The State (S8)
5.11 Polyatomic Ions:
Nitrate – NO 3 (1-)
Nitrite – NO 2 (1-)
Hydroxide – OH (1-)
bicarbonate (hydrogen carbonate) HCO 3 (1-)
Chlorate – ClO 3 (1-)
Carbonate – CO 3 (-2)
Sulfate – SO 4 (2-)
Phosphate – PO 4 (3-)
Ammonium – NH 4 (1+)
Electrolyte: a compound that separates into ions when it dissolves in water, producing a solution that conducts electricity.
6.3 law of conservation of mass: In any given chemical reaction, the total mass of the reactants equals the total mass of the products.
6.5,6.6,6.9 Types of reactions:
- A reaction in which 2 or more elements or compounds combine to form one single product
A + B --> AB
- A reaction in which one single compound is broken down into many smaller compounds or elements
AB --> A + B
- A reaction in which an element or ion moves out of one compound and into another
A + BC --> AC + B
- A reaction in which the anions and cations of 2 different molecules switch places
- AB + CD --> AD + CB
- A reaction in which oxygen combines with another compound to form water and carbon dioxide
i.e methane + oxygen -> water + carbon dioxide
7.1 Acids: aqueous solutions that conduct electricity, taste sour, turn blue llitmus red, and neutralize bases.
Bases: an aqueous solution that conducts electricity and turns red litmus blue. They are slipper and taste bitter.
pH: a pH of 7 is neutral. The scake goes from 0-14. pH is a mesure of...