Atoms & Elements
Explain why an atom is considered the smallest unit of matter that still retains the properties of an element.
It can not be separated or broken down into anything smaller.
Which number is the atomic number?
The top number
Compare dissolving sugar in water and burning sugar. Which is physical, which is chemical?
Dissolving-physical Burning-chemical
Identify at least three different types of evidence that could confirm a chemical reaction has occurred.
Temperature change, gas formation, color change, solid forming at the bottom, light production, odor change
What is solution?
A mixture of two or more substances.
Analyze why water (H₂O) and hydrogen peroxide (H₂O₂) are different substances even though they contain the same elements.
There is only 1 oxygen atom in water but there are 2 oxygen atoms in hydrogen peroxide.
What does the atomic number tell you about the element?
It tells you how many protons and electrons are in that element.
Evaluate why melting ice is considered a physical change even though it involves a change in state.
It is still water even though it changes the state. There was no chemical change to melt the ice.
Compare fireworks exploding and leaves changing color in the fall — how are these both examples of chemical change?
Fireworks there is a gas formation and odor change after the explosion. Leaves change colors and form a new substance.
What is one factor to increase the rate of dissolution besides temperature and stirring?
Particle Size
Predict what would happen to the properties of a compound if the ratio of elements in its formula changed.
It would totally change what the compound is and have different properties.
How many elements are on the periodic table?
109
Explain why rusting is a chemical change but cutting iron into smaller pieces is a physical change.
Rusting is changing the chemical composition of iron but cutting is creating smaller pieces.
Evaluate which type of evidence (temperature change, color change, gas production, etc.) is most reliable in identifying a chemical reaction, and justify your answer.
Gas production
Predict whether stirring or crushing a sugar cube would be more effective in increasing the dissolution rate, and explain why.
Stirring because crushing does not increase the collisions between particles like stirring does.
What does the subscript tell you about the atom in a chemical formula?
It tells you how many of that atoms are present.
How do you find the number of neutrons in an element?
Atomic mass - number of protons.
What is a physical property?
Something to describe a substance without altering it.
Why can we not always rely on color change as a chemical change.
Because if it was expected then it is not a chemical change, but if it was unexpected then it was a chemical change.
Explain dilution.
Adding water to a substance to make the concentration weaker.
Evaluate why mixtures can be physically separated while compounds cannot.
Mixtures are physically connected or combined but compounds are chemically combined or connected.
If tin (Sn) has 50 protons and electrons and 68 neutrons, what is the atomic mass?
118 amu
Predict the evidence you would observe if a new substance was formed during a reaction between two clear liquids.
If a solid formed at the bottom, there was a temperature change, there was a formation of bubbles or gas.
Analyze why “bubbles forming” in soda is not always evidence of a chemical change.
Because it is not forming a gas it a release of gas once the bottle or can is open.
Explain why increasing the temperature usually increases the rate at which a solute dissolves in a solvent.
It increase the collisions between molecules to increase the rate of dissolution.