Chemistry Midterm 2020 Flashcards
Lab safety rules
- Clean up after experiment
- No eating or drinking near lab
- Read procedure before
- Waft
- Wear safety goggles and lab coat
Steps of the Scientific Method
Purpose Research Hypothesis Experiment (materials and procedure) Analysis Conclusion
Length
use a ruler (cm or in)
Volume
rectangle: length x width x height cylinder: pour water into the graduated cylinder find the amount then place the object in, lastly subtract (L) formula: V = V2 – V1
Mass
tripe beam balance (g)
Density
– find the mass (g) find the volume (L) then divide the mass by the volume (g/ml)
Phase change
Solid to liquid – melting, adding energy
Liquid to solid – freezing, removing energy
Liquid to gas – evaporating, adding energy
Gas to liquid – condensation, removing energy
Motion of the molecules
Molecules in a solid – tightly packed, move slowly
Molecules in a liquid – loose, more not too fast, not too slow
Molecules in a gas – freely moving, gas move fast
How to identify substances
By its density, color, solubility and flame color
Six pieces of evidence that a chemical reaction
- gas produced
- light produced
- color change
- new odor
- temperature change (endothermic or exothermic)
- solid formed (precipitate)
Solutions and suspensions
Solution – - an evenly mixed mixture - same throughout - particles dissolve but their individual properties remain Suspension – - an unevenly mixed mixture - particles do not dissolve and settle to the bottom or float to the top - individual properties remain
Solutes and solvents
Solute – substance being dissolved
Solvent – substance that the solute is being dissolved into
How to find the number protons, electrons and neutrons
Number of protons = atomic number
Atomic mass = protons + neutrons
Same number of electrons as protons in a neutral atom
How to diagram an atom
Protons and neutrons in the nucleus and electrons orbiting around in shells
Basic information about an element based on its location
Left side = metals
Middle = metalloid
Nonmetal = right side
Left and second to last right groups are highly reactive, closer towards the middle less reactive, last right group is unreactive, and unattached two rows are radioactive.
Ionic bonds
between two oppositely charged ions, one metal and nonmetal
Valence electrons are given to the stronger ions to fill the last shell up
Ionic = 1.4 and up
Covalent bond
between two nonmetals, valence electrons are shared to fill the last shell
- Polar = 0.2-1.4
- Nonpolar = 0.0-0.2
How to identify the reactants and products.
Reactants = left side of the equation Products = right side of the equation
Law of Conservation of Mass
During a chemical reaction, mass is not created or destroyed, but it can be transformed into new combinations
How to tell if a substance is a acid or base
Acid pH level = 0-6
- 0-3 = strong acid
- 4-6 = weak acid
Base pH level = 8-14
- 8-10 = weak base
- 11-14 = strong baseHow to neutralize an acid or base
add the opposite
- If it’s an acid, add a base
- If it’s a base, add an acid
Electron Shells
First Shell: 2 Second Shell: 8 Third Shell:18 (Z< 21, then 8) Fourth Shell: 32 Fifth Shell: 32 Sixth Shell: 18 Seventh Shell 8
Metric unit conversion
KING HENRY DIED BY DRINKING CHOCOLATE MILK
Kilo, hecto, decta, base deci, centi, and milli
