Name _______________________________________________
Date _______________
Week 2 HONORS Homework
Purple Due: January 23 & Green Due: January 24
Bonding Review
1) How do bonds form?
2) What must happen in order to result in a chemical reaction?
3) Determine the formulas created when the following pairs of elements bond:
a. Calcium and Phosphorus _____ Ca3P2_____
b. Hydrogen and Fluorine
_____ HF _____
c. Barium and Silicon
_____ Ba2Si _____
In class we have learned how to determine the compound formula to determine how different elements
will bind together. Specifically we have been determining IONIC BONDS. Thus far you have learned that bonds
are formed when valence electrons are shared between elements. However, those electrons are not always
shared equally. In IONIC BONDS, elements steal electrons in order to bond.
In class we have witnessed this stealing happening. For example, hydrogen and fluorine bond together
to form HF. First we must identify the number of valence electrons each atom has, then we have to determine
what ion will form. Hydrogen loses 1 electron to form H+1, but where does that one electron go? Fluorine gains
1 electron to form F-1, but where does that one electron come from?
Fluorine actually takes that one electron away from Hydrogen! Thus, we form two different ions – a
cation and anion – that bond together forming an IONIC Bond. On the other hand, when valence electrons are
shared equally, that is known as a COVALENT BOND.
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IONINC BONDS are where electrons are stolen between elements.
COVALENT BONDS are where electrons are shared between elements.
Lewis Dot Structures are models that are used to represent the number of valence electrons in an element.
In a Lewis Dot Structure, each dot represents a valence electron. The periodic table can be used to write these
Lewis Dot Structures.
Lewis Dot Structure Steps:
1. Identify the number of valence electrons found in the neutral atom
2. Write the element Symbol
3. Add dots to represent the valence electrons from left to right adding one to each side
4) Practice Lewis Dot Structures
Element
Number of Valence
Electrons
Lewis Dot Structure
Neon
8
Ne
Strontium
2
Sr
Boron
5
B
Selenium
6
Se
Iodine
7
I
Lewis dot structures can also be used to represent bonds formed between different elements, whether it is
ionic bonds or covalent bonds.
When you draw Lewis dot structures for ionic bonds you show the anion stealing the electrons from cations
(see below).
However, when you draw Lewis Dot Structures for covalent bonds you show the elements sharing electrons
(see below).
Steps to drawing Lewis Dot Structures for Ionic Bonds:
1. Draw the Lewis dot structure for each neutral element represented in the compound formula
2. Circle the electrons being stolen from the element that will become the cation
3. Draw an arrow from the circled electron to the element that will become the anion
4) In the space below, draw the Lewis Dot Structures for the compounds you determined in question
3.
5) What is the difference between ionic and covalent compounds? Explain what happened with the
electrons that is different in the two types of bonding.
In ionic bonds, electrons are shared unequally. The anion in an ionic bond steals electrons from
the cation. Whereas, in covalent bonds, electrons are shared equally within bonds between
elements.
Physical and Chemical Properties
1) List 7 Physical Properties
______________Melting Temp____
____________Density___________
___________Color______________
_______________Shape_________
_____________Mass____________
_____________Volume__________
_______________Boiling Tem_____
2) List the 3 main chemical properties
_____________Acidity___________
______________Reactivity_______
_______________Magnetic_______
3) Which of the following is NOT a physical property?
a. Melting temperature
b. Density
c. Acidity
d. Color
4) Which of the following represents a chemical property?
a. Shape
b. Reactivity
c. Dissolvable
d. Color
5) In the following description of Sodium CIRCLE all physical properties described, and UNDERLINE all
chemical properties being described.
Sodium is a very soft metal, so soft it can be cut with a butter knife. When sodium is kept in an
air free environment it is white in color. When sodium openly sits in air, it readily reacts with
oxygen and turns a gray color. Also, sodium reacts violently with water and will generate a
flammable reaction if combined with water. Because Sodium is so soft, it has a low melting
temperature in comparison to other metals. In comparison to other metals in the same group as
Sodium, Sodium is more reactive compared to lithium and has less reactive properties than
potassium.
Lab Skills Practice
1) Write the number of the corresponding measurement in the space next to its correct units of
measurement.
a. mL ___2___
1. Mass
b. g/L ___3___
2. Volume
c. L ___2___
3. Density
d. g ___1___
2) Use the following word bank to match the correct tool of measurement to its proper label. Word
bank: graduated cylinder, cup, electronic balance, beaker, volume ruler
___electronic balance___
___beaker__________
___graduated cylinder__
3) Determine the volume of liquid in the following graduated cylinders. (Units of Measurement = mL)
4) An object has a mass of 216 g, and occupies a volume of 22 L. What is the density of this object?
Show your math below and don’t forget to label your units!
216g/22L = 9.82 g/L
5) A 12g object has a density of 3 g/mL. What is the volume of this object? Show your math below and
don’t forget to label your units!
V=m/d  V = 12g/3 g/mL = 4 mL
6) A. A graduated cylinder has 12 mL of water inside of it. When a marble is dropped into the
cylinder, the water level raises to the 14 mL mark. What is the volume of the marble? Show your
math below and don’t forget to label your units!
14mL – 12mL = 2 mL  volume of the marble
B. This marble has a density of 2 g/mL. Using the volume of the marble determine in part A,
determine the mass of the marble. Show your math below and don’t forget to label your units!
m=dxV  m = 2g/mL x 2 mL = 4 g
Physical vs. Chemical Change
1) Label each of the scenarios listed below either a C for chemical change, or a P for physical change.
a. Two clear solutions are added together. The resulting solution is s bright orange color C
b. A piece of metal is dropped into a liquid. The metal starts to fizz and the beaker warms up C
c. You put a wool sweater in the dryer. After drying you pull the sweater out and it has shrunk in
size P
d. Two clear solutions are added together. Solid white particles form in the beaker and sink to the
bottom C
e. You boil water on the top of your stove and steam is produced. P
2) CHALLENGE Question: In question 1 (d) from the Physical vs. Chemical Change section, which is
denser? The white solid or the liquid the solid is in? Explain how you know.
The white solid is denser then the liquid the solid is in because the solid sinks to the bottom of the
liquid. Therefore, if an object is denser than the substance that the object is placed in, then the
object will sink.