Science (Complete) PDF - Chemistry Notes

Lesson 2: FORMATION OF IONS IONS are simply charged atoms. How are ions formed? - Ions are formed as atoms gains or lose electrons. > Metals tend to lose electrons ELECTRONEGATIVITY is the ability of the atom to attract electron > Metals tend to lose electrons and form positively charged ion call...

Lesson 2: FORMATION OF IONS IONS are simply charged atoms. How are ions formed? - Ions are formed as atoms gains or lose electrons. > Metals tend to lose electrons ELECTRONEGATIVITY is the ability of the atom to attract electron > Metals tend to lose electrons and form positively charged ion called CATIONS > Non metals tend to gain electrons and form negatively charged ion called ANIONS TAKE NOTE! The number of electrons an atom gains or loses is its VALENCE How do you assign names for anion? Unlike a cation, which is named for the parent atom, an anion is named by taking the root name of the atom and changing the ending For example Cl Chlorine = Chloride How do you write chemical formulas with ions? For example: Sodium ion + Chlorine ion Na+ Cl- = NaCl Charge 1+ Charge 1- = Net Charge: 0 Lesson 3: Chemical Bonding CHEMICAL BONDING - A lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds Why do atoms bond? > Stable > Octet Rule > Ionic Bonding Ions formed after a metal atom transfer its VALENCE ELECTRON to nonmetal atom TYPES OF BONDING IONIC BONDING - is formed through complete transfer of electrons from one atom to another atom. It exists between metals and nonmetals. How does ionic bonding occur? Remember! > Metals tend to lose electrons (lower electronegativity values) > Nonmetals tend to gain electrons (higher electronegativity values) COVALENT BONDING - also called molecular bond, it is a chemical bond that involves sharing of electron pairs between atoms. - it commonly occurs when two nonmetals bond together RULES IN COVALENT BONDING - Compounds should obtain the 8 valence electrons (Octet Rule) -There is an exception in the octet rule like Hydrogen. Because each H atom has a filled valence shell, this bond is stable, and we have made a diatomic hydrogen molecule. (This explains why hydrogen is one of the DIATOMIC ELEMENTS). DI means 2 COVALENT BOND SHARING OF ELECTRONS Non polar covalent bond - equal sharing of electrons ex: H-H (No Electronegativity difference) Polar covalent bond - unequal sharing of electrons ex: H-F (Electronegativity difference) NON METALS have strong energy attractions or high electronegativity compared to metals WRITING CHEMICAL FORMULA The following general formula of a compound procedures may be followed in writing the: 1. The symbol/formula of the ion with positive oxidation number is written first followed by the symbol/formula of ions with negative oxidation number. 2. Balance the charges. The criss-cross method can help. The oxidation number of the positive ion becomes the subscript of the negative ion. If the subscript is 1, it is not written. If the subscript of the radical is greater than 1, the radical is enclosed in the parenthesis and the subscript is written outside the parentheses. The signs of the oxidation numbers are not written. Observe how the above procedures are applied to the following examples 3. If the oxidation numbers or charges of the positive and the negative ions are equal these are cancelled. 4. All subscripts should be simplified or reduced to the lowest ratio. NAMING COMPOUNDS - IONIC The following procedures may be applied in giving names to ionic compounds: 1. In naming binary ionic compound (composed of only two atoms, metal, and nonmetal, the name of metal is written first, followed by the name of nonmetal ending in -ide Examples: 1. NaCl sodium chloride 2. CaO calcium oxide NAMING COMPOUNDS COVALENT 1. In naming binary covalent compounds containing only one atom of the positive element, English name of the positive ion is written first then followed by the name of the negative ion with the proper prefix (indicating the number of atoms) ending with -ide. The following table lists some commonly used prefixes. Lesson 4: THE STRUCTURAL CHARACTERISTICS OF CARBON Example of Carbon: -Diamond -Battery -Fire Electric Configuration: 1s² 2s² 2p² Lewis Dot Structure: C Number 6 in the element of table Carbon > forms many organic compounds with many atoms > based molecules have three fundamental structures -Straight -Rings -Branched Isomers - One of two or more compounds that have the same chemical formula but different arrangements of the atoms within the molecules and that may have different physical/chemical properties. Bonding of carbon with itself ALLOTROPY is a behavior exhibited by certain chemical elements. ALLOTROPES a. Diamond b. Graphite c. Ionsdaleite d. Buckballs C60 e. Buckballs C540 f. Buckballs C70 g. Amorphous Carbon h. Carbon Nanotube Diamond > transparent and has no color > opaque and black > hard Graphite > soft and spongy > cannot conduct electricity > good conductor of electricity Similarities of both: > solid > non-gaseous > Insoluble in water Lewis Dot Structure of carbon - According To The OCTET RULE atoms need to have 8 valence electron - Atoms bond to become STABLE Hydrocarbon - only consists of hydrogen and carbon atoms. How to name hydrocarbon molecules Single Bond - Alkane Double Bond - Alkene Triple Bond - Alkyne Example: General Formula: Alkane: Cn H2 (n) + 2 Alkene: Cn H2 (n) Alkyne: Cn H2 (n) - 2 Alkane Example: n=3 C3 H2 (3) + 2 C3 H6+2 C3 H8 Alkene Example n=3 C3 H2 (3) C3 H6 H H H | | | C = C-C—H | | H H Alkyne Example n=3 C3 H2 (3) - 2 C3 H6 - 2 C3 H4 H | C =(Three lines) C - C — H | | H H