A mixture is a substance that includes more than one type of element and/or compound that are not bonded together.
100
Define the word “compound.”
A compound is a substance whose smallest particles include more than one element chemically bonded together.
100
What exactly is a chemical formula? (What is the definition?)
A chemical formula gives the symbols and amounts of each type of atom in a compound.
100
Define an ion.
An atom that has a positive or negative electric charge. Ions are created when atoms gain or lose electrons.
100
DEFINE Lewis dot diagram.
A Lewis dot diagram show the valence electrons for an element.
200
How can a mixture be separated into its original parts?
A mixture can be separated by physical means, using the properties of the substances in it.
200
How many compounds can be made from the atoms on the Periodic Table?
Millions!
200
Write the chemical formula for carbon dioxide ( 1 carbon atom and 2 oxygen atoms)
CO2
200
How can you tell if an ion is positive or negative?
A positive ion has a positive charge because it gave away an electron, so now its protons outnumber electrons. A negative ion has a negative charge because it gained an electron, so its electrons outnumber its protons.
200
Draw the Lewis dot diagram for magnesium.
*
Mg *
300
When salt is added to water, is that a mixture or a compound, and why?
Salt water is a mixture. The water is still water, and the salt it still salt. They can be separated by evaporation.
300
What is a chemical bond?
A chemical bond is when a bond is formed between atoms by the sharing or transferring of electrons.
300
This is the chemical formula for glucose - C6H12O6 What does it tell you?
This formula tells you that the molecule has 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms.
300
What keeps an ionic compound together?
The atoms in ionic compounds are attracted to each other by their electric charges.
Each positive ion is attracted to all of the neighboring negative ions, and vice-versa.
300
Draw the Lewis Dot Diagram for gallium (Ga).
*
Ga *
*
400
Is iced tea a mixture or a compound, and why?
Ice tea is a mixture. All the parts retain their identity (water, tea, sugar, lemon) and it is possible to separate the parts.
400
Define a covalent bond.
A type of chemical bond that is formed by sharing electrons.
400
What can a chemical formula for a molecule tell you about the type of compound?
If it is one metal and one non-metal, is is an ionic compound. If it is two metals, it is a metallic compound. If it contains C, H, and O it is probably covalent.
400
Which two groups are the most reactive, and why?
Group 1 (alkali metals ) and Group 7 (halogens) because they are very close to the magic number (only have to share or give away 1 electron to get to same number of valence electrons as a noble gas - 8)
400
Draw the Lewis Dot Diagram for silicon (Si).
*
* Si *
*
500
List some of the physical properties that can be used to separate a mixture.
Size, magnetism, solubility, change of phase (evaporation, changing from liquid to solid).
500
Define “molecule” and give two examples
A molecule is a group of atoms held together by covalent bonds.
Some examples are:
methane (CH4), ammonia (NH3), oxygen (O2), nitrogen (N2) and water (H2O).
500
What is the little number down to the right of the element symbol called?
This is the subscript. It tells you the number atoms of the element in the compound.
500
Explain why the Noble Gases are not reactive.
Noble gases have 8 valence electrons and this means that they don’t have to share or get any electrons to get to the magic number - they are already there.