Download Science notes for Ionic and Covalen Bonds and more Cheat Sheet Earth science in PDF only on Docsity!
Chemical Bonding Study Guide
Ionic vs. Covalent Bonds - 8th Grade Honors
What are Chemical Bonds?
Chemical bonds are the forces that hold atoms together to form compounds. Atoms form bonds to become more stable by achieving full outer electron shells (usually 8 electrons).
Ionic Bonds
Definition
Ionic bonds form when atoms transfer electrons from one atom to another Occurs between metals and non-metals Creates charged particles called ions
How They Form
Metal atoms lose electrons and become positively charged (+) Non-metal atoms gain electrons and become negatively charged (-) Opposite charges attract, creating the bond
Examples
Sodium chloride (NaCl) - table salt Na gives up 1 electron to ClNa becomes Na⁺, Cl becomes Cl⁻ Magnesium oxide (MgO) Mg gives up 2 electrons to O Mg becomes Mg²⁺, O becomes O²⁻
Covalent Bonds
Definition
Covalent bonds form when atoms share electrons Occurs between non-metal atoms Creates neutral molecules
How They Form
Atoms share electrons to fill their outer shells Can share single, double, or triple pairs of electrons Forms strong connections between atoms
Examples
Water (H₂O) Each H shares 1 electron with OO shares 2 electrons total (1 with each H) Carbon dioxide (CO₂) C forms double bonds with each O Shares 4 electrons total Key Differences Lewis Diagrams
Quick Steps to Draw Lewis Diagrams
Step 1: Count valence electrons (group number on periodic table) Step 2: Put the element symbol in the center Step 3: Add dots around the symbol - one at a time on each side Step 4: Pair up electrons only after each side has one dot
Examples
Oxygen (O) - 6 valence electrons :O:
... Property Ionic Bonds Covalent Bonds Electron behavior Transfer electrons Share electrons Types of atoms Metal + Non-metal Non-metal + Non-metal Resulting particles Ions (charged) Neutral molecules Melting point Usually high Usually lower Conduct electricity? Yes (when dissolved) No
Not simplifying subscripts
Ionic Compounds
Covalent Prefixes (When to Use)
Complete Prefix Chart
When to Use Prefixes
Use prefixes when: Both elements are non-metals (covalent compounds) You need to show the exact ratio of atoms Don't use prefixes when: It's an ionic compound (metal + non-metal) The first element only has 1 atom (mono- is usually dropped) Easy Memory Trick: "Mono is lonely - usually alone!" Examples: CO = carbon monoxide (not monocarbon monoxide) Number Prefix Example 1 mono- carbon monoxide (CO) 2 di- carbon dioxide (CO₂) 3 tri- sulfur trioxide (SO₃) 4 tetra- methane (CH₄) 5 penta- phosphorus pentachloride (PCl₅) 6 hexa- sulfur hexafluoride (SF₆) 7 hepta- iodine heptoxide (I₂O₇) 8 octa- octasulfur (S₈) 9 nona- nonane (C₉H₂₀) 10 deca- decane (C₁₀H₂₂)
CO₂ = carbon dioxide (not monocarbon dioxide) N₂O = dinitrogen monoxide NaCl (table salt) MgO (magnesium oxide) CaCO₃ (calcium carbonate) Fe₂O₃ (rust)
Covalent Compounds
H₂O (water) CO₂ (carbon dioxide) O₂ (oxygen gas) CH₄ (methane) Quick Tips for Identifying Bond Types
Look at the elements:
Metal + Non-metal = Ionic Two non-metals = Covalent
Check the periodic table:
Left side = metals Right side = non-metals Stair-step line separates them
Remember the "Big Three":
NaCl - classic ionic H₂O - classic covalent CO₂ - covalent with double bonds Practice Problems
Identify the bond type:
- KBr (potassium bromide) = _______
- NH₃ (ammonia) = _______
- SO₂ (sulfur dioxide) = _______
Answers:
- Ionic (metal + non-metal)
