1. Define Physical Change. Physical changes occur when objects undergo a change that does not change their chemical nature. 2. Define Chemical Change.
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Physical changes occur when objects undergo a change that does not change their chemical nature.
A match burns
A tree is cut down
Sodium reacts with water to make sodium hydroxide
Rusting of iron
Boiling of water
Digestion of food
Boiling an egg.
Melting of ice
Circle the chemical changes
The boiling point of water is 1000 C
The density of ice is lower than liquid water
Water reacts violently with sodium
Hydrogen burns with a popping sound.
The color of Copper compounds is blue.
The correct answer is D .The properties of shale do not change when it shatters.
B. Separating the water into its elements –freezing water, calculating the density of water, or dissolving sugar in water do not change the properties of water.
D. In rusting, the metal combines with other atoms.
Adjust the density formula and solve the problems below:
Viscosity is the resistance of a fluid to flow.
Honey is more viscous than water.
Hot honey flows faster than cold honey.
Water is more dense than oil so forms a layer below oil.
Density = 10.49 g/cm3
Volume= 12.993 cm3,
10.49g/cm3 x 12.993cm3 =136.3 g
Sometimes a question will give you too much information.
Focus on what you are looking for – Mass
Mass = Density x volume
=1.83g/ml x 12ml
=21.96 g= 22.0g
The only object that has adensity less than 1 is D.
= 1.23g/ml x 19.4ml=23.9 g
The density does not change when something is cut in half. The density of the two smaller blocks will also be 19.3 g/cm3
Circle the mixtures and underline the elements from the following list.
An element is made up of only one kind of atom. A compound is made of two or more elements combined together in a fixed ratio.
Protons and neutrons are present in the nucleus of an atom.
An atom loses an electron to form a positive ion.
Group : 1
Valence electrons : 1
Ion formed : +1
Group : 17
Valence electrons : 7
Ion formed : -1
Group : 18
Valence electrons : 8
Does not lose or gain electrons
Group : 16
Valence electrons : 6
Ion formed : -2
Metals, Nonmetals and Metalloids on the Periodic Table
Located on the ______ side
Conduct heat and electricity
located __________ the metals and non-metals
Have properties of both metals and non-metals
______ at room temperature
1. Which of the following elements is a metal?
1. Which element has properties that are chemically most similar to the element Se?
Te is in the same group as Se and so would be chemically similar to it.
Mass number is the total number of protons and neutrons in the nucleus of an atom.
C, N, O
C, N, P
N, P, As
Ge, As, S
N, P and As belong to the same group and therefore are most chemically similar.
Alkaline earth metals
Noble gases have 8 valence electrons; their outer energy levels are complete and so they do not react with anything and are resistant to forming compounds.
Halogens – Group 17 have 7 valence electrons, they need only one more to complete their octet .This group therefore accepts electrons most readily
Potassium has 1 valence electron. When it loses the one valence electron, it now has 8 in its outer energy level.
Answer - B
Be in group 2 has 2 valence electrons , so it will donate two electrons.
Cs has one valence electrons so it will donate one valence electron.
The correct answer is G
The correct answer is T.
The other element which will have the same properties as calcium should be in the same group as calcium – which is strontium.
1. An example of ionic bonding is between _________.
a metal and a metal
a metal and a nonmetal
a nonmetal and a nonmetal
When atoms bond using covalent bonding the atoms share electrons in their outer shell creating full shells for both.
a) Magnesium and Oxygen
b) Potassium and chlorine
c) Carbon and chlorine
d) Sodium and Sulfur
e) Sulfur and oxygen
Swap and Drop B2 (CO3)3
Group 16 elements have 6 valence electrons ,they need two more to become stable – Magnesium is able to donate those two electrons as it is in group 2 and so an ionic bond is formed between one Magnesium atom and one Oxygen atom.
Law of conservation of mass states that mass can neither be created nor destroyed.
The total mass of the reactants is equal to the total mass of the products.
The 6 in front of water is the coefficient and it means 6 molecules of water.
The shape of a water molecule is _______. This makes water an extremely good solvent. Water is a universal solvent as it is able __________ a number of substances. Water molecule is polar in nature because the oxygen has a negative charge and hydrogen has a positive charge .
Water is unique because liquid water is _____ dense then ice. Ice is able to float on water. This helps fish to survive in extreme cold.
H. Expand when it freezes ,creating a floating and insulating layer of ice.
Factors that affect the rate of reaction:
Surface area- Crushing INCREASES surface area.
The correct answer is D.
Properties of acids
Acids are sour to taste
Acids turn blue litmus red
Acids react with bases to form salt and water
Acids are corrosive
Ph of an acid is less than 7
Strong acids are strong electrolytes
HCl- Hydrochloric acid
Sulfuric acid – H2SO4
Phosphoric acid –H3PO4
Hydrobromic acid -HBr
Nitric Acid –HNO3
Examples of bases
NaOH- Sodium Hydroxide
Ba (OH) 2- Barium Hydroxide
Ammonia – NH3
Calcium Hydroxide – Ca (OH)2
Bases have a high concentration of OH- ions
Water has an equal amount of H+ and OH- ions.
Water has a pH of 7
3. Define electrolyte.
4. Why is NaCl a strong electrolyte?
The salts in tap water fall apart into electrically charged particles (ions) in water. In an electrical field, these ions are dragged one way or the other, depending on their charge, producing an electric current .
From distilled water all ions have been removed, so it does not conduct electric current .