Mixture? Element? Compound?
Is air a mixture or a compound?
Air is a mixture made up of compounds.
How do ions form?
Ions form when an atom either gives away or receives electrons, causing an imbalance between the number of protons and electrons.
Are elements really sharing electrons in a covalent compound? Explain.
No, each element is trying to take the other's electrons and they are fighting over them.
In this type of bond molecules form.
covalent
How do you write the formula dinitrogen trioxide?
N2O3
Is N2 an element or a compound? Explain.
It is an element. Although the atoms of nitrogen are chemically combined, it is only made up of one type of element and does not have new and completely different properties.
What are the two types of ions and how to they form?
Anions are negative ions and they form when an atom receives electrons giving it more electrons than protons. Cations are positive ions and they form when an atom gives away electrons leaving it with more protons than electrons.
Sugar has a chemical formula of C12H22O11. Explain why it why it is a covalent compound.
Since three nonmetals make up the compound, there will be sharing of electrons, not give and take.
In this type of bond oppositely atoms are attracted to one another and crystals form.
ionic
How do you say N2O4?
dinitrogen tetroxide
Explain how we knew that the salt water we mixed class was a mixture and not a compound?
Once the water evaporated, the salt was left behind. A property of a mixture that is different from a compound is that it can be separated by physical means.
Can elements that do not have a 1:1 ratio still form an ionic compound? Explain.
Yes. if a metal has more electrons to give than a nonmetal has spaces to take, that means that subscripts will be used in the formula to show the ratio or number of atoms of each element in the compound.
What type of elements are likely to form covalent compounds? Why?
Two nonmetals bonding will likely form a covalent bond, because both want to take the other's electrons, with the end result being that they share space.
In this type of bond two or more elements chemically combine to form a new substance with new properties.
both
What is the ratio of sodium and chlorine in sodium chloride? Explain.
The ration is 1:1. Since the oxidation number of sodium is 1+ and the oxidation number of chlorine is 1- you have a 1:1 ration when they form a compound.
When we mixed sugar and water in class we could no longer see the sugar. Was this a chemical reaction, since we could no longer see the properties of the sugar?
No, this is still a physical change, not a chemical change. The sugar dissolved into the water creating a solution (very evenly mixed mixture). If we heated the water so that it evaporated, we would be able to separate it from the sugar.
Is methane (CH4) an ionic compound? Explain.
Methane is a not an ionic compound because it is made of two nonmetals, both of which want to take electrons, forming the same type of ion. Two of the same type of ion will repel, not attract.
What kind of covalent bond is O2? Explain.
This is a double covalent bond, which means the two atoms share two, not one pair of electrons.
In this type of bond electrons share space as the positive nucleus of each atom fights to take the other's electrons.
covalent
What is the chemical formula for Aluminum Oxide, if aluminum has an oxidation number of 3+ and oxygen has an oxidation number of 2-?
Al2O3
Compare mixtures and compounds.
Mixtures are not chemically combined and therefore can usually be separated by fairly simple means, and each substance in the mixture keeps its properties. Compounds are chemically combined, so the new substance has totally different properties than the substances that are combined to create it.
Why do ionic compounds form between metals and nonmetals?
Since metals have a lower number of valence electrons, they want to give them away to fill their outer shell, causing them to become cations. But nonmetals have a higher number of valence electrons, so they want to take electrons to fill their outer shell, causing them to become anions. The two oppositely charged ions attract to form a strong bond.
Does each element always pull equally on the electrons in a covalent bond? Explain.
No, sometimes one pulls more than the other, resulting in a molecule that is slightly negative on one side and slightly positive on the other. This is called a polar covalent bond.
In this type of bond the rearrangement of electrons forms a compound that is more stable than the elements were independently.
What is NO3- and what does that mean?
It is an example of a polyatomic ion. That means that the nitrogen and oxygen bonded but are still not stable, so, as a unit, they want to take electrons from another element to form an ionic bond and stabilize.