Materials Science CH 1-5

What is Materials Science?

The study of the structure, properties, processing, and performance of materials.

What is Materials Engineering?

The application of materials science principles to design and manufacture useful products.

What are the four main categories of materials?

Metals, Ceramics, Polymers, and Composites.

What is the difference between metals and ceramics?

Metals are good conductors of electricity and heat, while ceramics are brittle and have high melting points.

What is Young’s Modulus?

A measure of a material's stiffness, defined as stress divided by strain in the elastic region.

What are the three types of material bonds?

Ionic (electron transfer), Covalent (electron sharing), and Metallic (electron sea).

What is an isotope?

Atoms of the same element with different numbers of neutrons.

What is the atomic number?

The number of protons in an atom, which defines the element.

What is the mass number?

The total number of protons and neutrons in an atom.

What is Avogadro’s number?

6.022 x 10^23, representing the number of atoms or molecules in one mole.

How do you calculate atomic weight from isotopes?

Multiply the mass of each isotope by its fractional abundance and sum the values.

What is the Bohr model of the atom?

A model where electrons orbit the nucleus in fixed energy levels.

What is the Law of Conservation of Mass?

Matter cannot be created or destroyed in a chemical reaction.

How do you balance a chemical equation?

Adjust coefficients to ensure the same number of each type of atom on both sides.

What is the difference between empirical and molecular formulas?

Empirical formula shows the simplest ratio, molecular formula shows the actual number of atoms.

Balance the equation: H2 + O2 → H2O

2H2 + O2 → 2H2O.

What is a mole in chemistry?

A unit representing 6.022 x 10^23 particles of a substance.

How do you convert moles to grams?

Multiply the number of moles by the molar mass of the substance.

What is a limiting reactant?

The reactant that is completely used up, determining the maximum amount of product.

Solve: If 5.0 moles of CH4 react with excess O2, how many moles of CO2 are produced? (CH4 + 2O2 → CO2 + 2H2O)

5.0 mol CH4 × (1 mol CO2 / 1 mol CH4) = 5.0 mol CO2.

How do you calculate percent yield?

Divide the actual yield by the theoretical yield and multiply by 100%.

What is Boyle’s Law?

P1V1 = P2V2 (At constant temperature, pressure and volume are inversely proportional).

What is Charles’ Law?

V1/T1 = V2/T2 (At constant pressure, volume is directly proportional to temperature in Kelvin).

What is the Ideal Gas Law equation?

PV = nRT.

Solve: A gas has a volume of 3.0 L at 250 K. What is its volume at 500 K if pressure remains constant?

Using Charles’ Law: V2 = (3.0 L × 500 K) / 250 K = 6.0 L.

What are the three main types of chemical bonding?

Ionic (transfer of electrons), Covalent (sharing of electrons), Metallic (electron sea model).

What is electronegativity?

An atom's ability to attract electrons in a chemical bond.

What is a polar covalent bond?

A covalent bond where electrons are shared unequally, creating partial charges.

What are strong electrolytes?

Substances that completely dissociate into ions in water, conducting electricity.

What are weak electrolytes?

Substances that partially dissociate into ions in water.

What is molarity?

Molarity (M) = moles of solute / liters of solution.

Solve: What is the molarity of a solution containing 0.5 moles of NaCl in 1.5 L of water?

Molarity = 0.5 moles / 1.5 L = 0.333 M.

What is the percent composition formula?

Percent composition = (mass of element / total mass of compound) × 100%.

What is the difference between diffusion and effusion?

Diffusion is the spreading of gas particles, while effusion is the movement of gas through a small hole without collisions.

What is Graham’s Law of Effusion?

The rate of effusion is inversely proportional to the square root of the molar mass of the gas.