WEEK 2 - Minerals & Gems Flashcards
What is a Mineral?
Defining Features of a Mineral:
- Naturally occurring (not man-made).
- Solid (not liquid or gas).
- Inorganic (not from living things).
- Has a definite chemical composition (specific elements in a fixed ratio).
- Crystalline structure (atoms arranged in an orderly pattern).
- Ice is considered a mineral
- Most rocks are made of aggregated mineral crystals or particles
What are Minerals Made Of?
Minerals = Elements – They are composed of chemical elements.
Elements Defined – Cannot be broken down into simpler substances.
Common Elements in Minerals – Hydrogen, helium, oxygen, carbon, calcium.
Not Minerals! – Manganese, selenium, chromium are elements, not minerals.
How Many Elements Exist? – Over 100 elements, with 92 naturally found on Earth.
Atomic Structure
Atom - The smallest unit of matter that keeps an element’s properties
Nucleus - Center of the atom, made of protons (+) and neutrons (0) (most of the atoms mass)
Electrons - Orbit around the nucleus in cloud-like shells, defining energy levels
Valence Electrons - Found in the outermost shell, important for bonding
Subatomic Particles
The smaller building blocks of an atom, the three main types are:
Proton – Charge: +1, Mass: 1
Neutron – Charge: 0, Mass: 1 (stabilize the nucleus)
Electron – Charge: -1, Mass: almost 0
Periodic Table of Elements
Elements are organized according to their weight and other characteristics
How Are Elements Shown in the Periodic Table?
Atomic Number = # of Protons – Every element has a set number of protons (Carbon = 6)
Element Symbol – Abbreviation of the element’s name (C = Carbon)
Atomic Weight – Total mass of protons, neutrons, and electrons (Carbon ≈ 12.011)
Element Name – Full name of the element (e.g., Carbon)
Why Do Atoms Bond?
Electron Shells Need to Be Full – Atoms want full outer shells for stability
Shell Capacity – Inner shell = 2 electrons, Outer shells = 8 electrons
Unfilled Shells = Bonding – Atoms share, gain, or lose electrons to become stable
Ionic Bonding: The Electron Exchange
How It Works – One atom gives away electrons, another takes them
Positive Ion (Cation) – Loses electrons (e.g., Sodium Na⁺)
Negative Ion (Anion) – Gains electrons (e.g., Chlorine Cl⁻)
Why? – This creates a strong attraction between oppositely charged ions
Example:
Sodium (Na) + Chlorine (Cl) = Table Salt (NaCl)
Sodium Gives an Electron – Becomes Na⁺ (positive ion)
Chlorine Accepts It – Becomes Cl⁻ (negative ion)
Result = Ionic Bond – Opposites attract, forming NaCl (salt)!
How Does Salt (Halite) Form?
Opposites Attract – Positive sodium ions (Na⁺) bond with negative chloride ions (Cl⁻)
Forms Sodium Chloride (NaCl) – A mineral called Halite
Halite = Table Salt – The same salt we eat!
How Do Atoms Share Electrons? (Covalent Bonding)
When Two Atoms Want More Electrons – Instead of giving them away, they share!
Example: Two Chlorine Atoms (Cl₂) – Each has 7 outer electrons and needs 1 more
Solution: They Share One Electron Each – This forms a covalent bond, creating a chlorine molecule (Cl₂)
How Does Salt (Halite) Get Its Shape?
Ionic Bonding Creates a Cube Structure – Sodium and chloride ions arrange in a repeating pattern
This Regular Pattern = Crystal Shape – This is why salt forms cubic crystals
Covalent Bonding in Minerals
Some Minerals Are Also Covalently Bonded – Example: Diamonds 💎
Diamond = Pure Carbon (C) – Each carbon atom shares electrons with 4 others, creating an extremely strong covalent structure
What If Two Atoms Want Electrons?
Example: Two Chlorine Atoms
Each chlorine has 7 electrons in its outer shell
They need 1 more to reach 8
Solution: They SHARE electrons → This forms a Covalent Bond!
Intermolecular Bonding (Weak Attractions)
What is Intermolecular Bonding? – Weak forces between molecules (not inside them)
Example: Water Molecules 💧 – The slightly positive hydrogen in one water molecule attracts the slightly negative oxygen in another, forming weak “van der Waals” forces
These Bonds Are Easy to Break – This is why water flows easily and evaporates with heat
Mineral Properties (What Determines Them?)
Chemical composition & crystal structure define appearance & behavior
Lab tests can identify minerals, but they are expensive & time-consuming
Some minerals are valued for their beauty & usefulness (e.g., gems 💎)
Quartz: A Covalent Mineral
Quartz = Silica (Silicon + Oxygen)
Each Silicon (Si) atom bonds with 4 Oxygen (O) atoms
Oxygen atoms share electrons with Silicon, forming a strong covalent network
This structure gives Quartz its hardness and crystal shape
Intermolecular Bonding in Minerals
Graphite (in Pencils ✏️) - Carbon atoms have strong covalent bonds, but weak forces hold the layers together
- These weak bonds make graphite layers rub off easily on paper
Mica Minerals (Flaky Appearance) - Mica has strong covalent bonds within layers, but weak forces between layers, making it peel in thin sheets
Metallic Bonding (How Metals Stay Strong & Conduct Electricity ⚡)
What is Metallic Bonding? – Metal atoms “float” in a sea of free electrons, allowing easy movement
Why Are Metals So Conductive? – Free-moving electrons carry electricity (like in copper wires 🧵🔌)
Metals Are Malleable – Because the atoms can slide past each other, metals can be shaped easily (like gold and silver jewelry 💍)
Why Do Mineral’s Have Specific Shapes?
Atoms arrange in patterns that form distinct crystal shapes
The way atoms pack together determines a mineral’s external geometry
Examples of Crystal Forms/Shapes
Halite (NaCl - Table Salt) 🧂 → Cubic shape
Quartz (SiO₂) ⬡ → Hexagonal prisms
Diamond (C) 💎 → Octahedra (sometimes cubes)
Minerals aren’t just random chunks—their atomic structure gives them unique geometric shapes! 🔷
Cleavage
How minerals break apart
What is Cleavage?
Minerals break along weak atomic bonds, forming smooth surfaces
This breakage follows specific planes in the crystal structure
Example: Mica Minerals ✂️
- One-directional cleavage due to weak bonds between atom layers
- This gives mica its sheet-like structure (used in glitter ✨)
Multiple Cleavage Directions
Some minerals have more than one cleavage direction:
- Fluorite 🟣 → 4 cleavage directions (octahedral)
H- alite (NaCl) 🧂 → 3 cleavage directions at 90° (cubic)
- Calcite ⚪ → 3 cleavage directions NOT at 90° (rhombohedral)
Cleavage Planes vs. Crystal Faces
Key Differences:
Crystal Faces = external shape of a mineral.
Cleavage Planes = internal breakage pattern along weak atomic bonds
Crystals keep their shape, but cleavage happens predictably along weak planes
💡 Example: Quartz (left) has a distinct crystal shape, but doesn’t cleave easily like calcite (right)
