Topic 1: Stoichiometric Relationships Flashcards
What is the Atomic Theory?
- All matter is composed of atoms.
- These atoms cannot be created or destroyed, and are rearranged during chemical reactions.
- Physical and chemical properties of matter depend on the bonding and arrangement of these atoms.
Summarize the properties of a solid:
- fixed volume
- fixed shape
- cannot be compressed attractive forces between particles hold the particles in a close-packed arrangement
- particles vibrate in fixed positions
Summarize the properties of a liquid:
- fixed volume
- no fixed shape - takes the shape of the container it occupies
- cannot be compressed
- forces between particles are weaker than in solids
- particles vibrate, rotate, and translate (move around)
Summarize the properties of a gas:
- no fixed volume
- no fixed shape - expands to occupy the space available
- can be compressed
- forces between particles are taken as zero
- particles vibrate, rotate, and translate faster than in a liquid
What is the definition of temperature and what is its SI unit?
Temperature is a measure of the average kinetic energy of the atoms or molecules in the system. The SI unit for temperature is the kelvin, K.
What happens when the temperature is an absolute zero and when the temperature is greater than absolute zero on the Kelvin scale?
Absolute zero on the kelvin scale means when the temperature at which all movement particles
stops. When the temperature is greater than an absolute zero, all particles vibrate, even in solid matter.
Convert temperature from the Celsius scale to the Kelvin scale.
temperature (K) = temperature (°C) + 273.15
Liquid → Solid
Freezing
Solid → Liquid
Melting
Liquid → Gas
Vaporization
Gas → Liquid
Condensation
Gas → Solid
Deposition
Solid → Gas
Sublimation
What is matter?
Matter is any substance that occupies space and has mass.
What are two groups matter is classified into?
Mixtures and pure substances.
What is a mixture?
A mixture is a combination of two or more pure substances that retain their individual properties.
What are the two groups that mixture us classified into?
Homogeneous mixture and heterogeneous mixture.
What are homogeneous mixtures? Give and example.
The homogeneous mixture has both uniform composition and properties throughout.
Example. Salt water, metal alloys
What are heterogeneous mixtures? Give an example.
Heterogeneous mixture has non-uniform composition and varying properties.
Example. Salad dressing, paint, garden soil.
What are pure substances?
Pure substances has a definite and constant composition.
What are two groups pure substances is classified into?
Elements and compounds.
What are elements? Give an example.
Elements are made up of atoms that each have the same atomic number.
Example. Lead, Mercury.
What are compounds? Give an example.
Compounds are made up of a combination of atoms or ions in a fixed ratio and have different properties from the constituent elements.
Example. Water, carbon dioxide, sodium chloride.
What is an Ion?
An ion is a charged particle.
What is the difference between an anion and cation?
Anions are negatively charged while cations are positively charged.
What is atom economy and state its formula?
Atom economy is a measure of the desired useful products from reactants in a chemical reaction and stated as a percent.
percentage atom economy = (molecular mass of atoms of useful products / molecular mass of atoms in reactants) x 100%
Define “The Mole”.
The mole is an SI unit, symbol mol, defined as a fixed amount, n, of a substance.
What is Avogadro’s constant?
Avogadro’s number, L, is the number of units in one mole of any substance. The units being 6.02 x 10^23 mol^-1.
What are isotopes?
Isotopes are atoms of the same element hat have the same number of protons in the nucleus but differnt numbers of neutrons.
Define “Molar Mass”.
The molar mass is defined as the mass of one mole of a substance. It has the unit of grams per mole, g/mol.
* The molar mass of a substance contains Avogadro’s number of representative particles (the particles may be atoms, molecules, or ions)
Number of Particles → Moles
÷ Avogadro’s Constant, L
Moles → Number of Particles
x Avogadro’s Constant, L
Moles → Grams
x Molar mass
Grams → Moles
÷ Molar mass