Chemistry Midterm 2020

Question 1

Lab safety rules

Answer 1

1. Clean up after experiment
2. No eating or drinking near lab
3. Read procedure before
4. Waft
5. Wear safety goggles and lab coat

Question 2

Steps of the Scientific Method

Answer 2

Purpose
Research 
Hypothesis 
Experiment (materials and procedure)
Analysis
Conclusion

Question 3

Length

Answer 3

use a ruler (cm or in)

Question 4

Volume

Answer 4

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

Question 5

Mass

Answer 5

tripe beam balance (g)

Question 6

Density

Answer 6

– find the mass (g) find the volume (L) then divide the mass by the volume (g/ml)

Question 7

Phase change

Answer 7

Solid to liquid – melting, adding energy
Liquid to solid – freezing, removing energy
Liquid to gas – evaporating, adding energy
Gas to liquid – condensation, removing energy

Question 8

Motion of the molecules

Answer 8

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

Question 9

How to identify substances

Answer 9

By its density, color, solubility and flame color

Question 10

Six pieces of evidence that a chemical reaction

Answer 10

1. gas produced
2. light produced
3. color change
4. new odor
5. temperature change (endothermic or exothermic)
6. solid formed (precipitate)

Question 11

Solutions and suspensions

Answer 11

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

Question 12

Solutes and solvents

Answer 12

Solute – substance being dissolved

Solvent – substance that the solute is being dissolved into

Question 13

How to find the number protons, electrons and neutrons

Answer 13

Number of protons = atomic number
Atomic mass = protons + neutrons
Same number of electrons as protons in a neutral atom

Question 14

How to diagram an atom

Answer 14

Protons and neutrons in the nucleus and electrons orbiting around in shells

Question 15

Basic information about an element based on its location

Answer 15

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.

Question 16

Ionic bonds

Answer 16

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

Question 17

Covalent bond

Answer 17

between two nonmetals, valence electrons are shared to fill the last shell

• Polar = 0.2-1.4
• Nonpolar = 0.0-0.2

Question 18

How to identify the reactants and products.

Answer 18

Reactants = left side of the equation
Products = right side of the equation

Question 19

Law of Conservation of Mass

Answer 19

During a chemical reaction, mass is not created or destroyed, but it can be transformed into new combinations

Question 20

How to tell if a substance is a acid or base

Answer 20

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 base

Question 21

How to neutralize an acid or base

Answer 21

add the opposite

• If it’s an acid, add a base
• If it’s a base, add an acid

Question 22

Electron Shells

Answer 22

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

Question 23

Metric unit conversion

Answer 23

KING HENRY DIED BY DRINKING CHOCOLATE MILK

Kilo, hecto, decta, base deci, centi, and milli