Chemistry Cheat Sheet
Why do ionic bonds form between metals and nonmetals? –> metals form positive ions and nonmetals form negative ions. The positive ion is a cation and the negative is the anion. Nonpolar covalent bond vs polar covalent bond? due to electro negativities that affect how the atoms will share electrons. A non polar covalent bond has an electro negativity of . 4 or less. A polar covalent has greater then . 4 less 2 How many electrons must a calcium atom gain or lose? Calcium has to lose 2. It originally is at Ca2+ Why do some substances undergo chemical reactions and some do not?
Bc of their electron configuration. If one substance has an unbalanced set of valance e- and so does another substance, then they will bond and each will have a complete set. The valance e- in the e- configuration determines if they will undergo chemical reactions. How can you tell whether a chemical equation is balanced? What principle is reflected in the balanced equation? If they have the same number of atoms on each side of the equation. Example: the equation couldn’t be balanced if there were 2 hydrogen atoms on 1 side and 4 on the other.
The scientific principle that reflects the balanced equation is the law of conservation of matter. Matter cannot be created nor destroyed just like atoms cannot be either. You cant create an unbalanced number of atoms on one side or destroy one atom to make it balanced. Balanced equation for reaction where calcium nitride is formed from calcium and nitrogen? 3Ca+N2Ca3N2 Aluminum reacts with fluorine to produce aluminum fluoride. 2Al + 3F2 2AlF3 There are 2 Al’s and 6 F’s. 3Cl2+N22NCl3 …. Chlorine + nitrogen yields to nitrogen tri chloride.
Name the compound with the formula (NH4)3PO4 Ammonium Phosphate Max number of Hydrogens = 8 picture Carbon tetrachloride- 160 amu…sulfuric acid-98 amu…phosphorus pentoxide- 142 amu State the relationship between volume and number of moles of a gas? At the same temperature & pressure, equal volumes of gases will contain the same number of gas particles. STP: standard temperature and pressure. **6. 02 x 1023 particles of any gas at STP will have a volume of 22. 4 liters. Volume of 1 mole of gas at STP. Explain how to find the formula mass of a molecule by using the info in a periodic table.
Look at atomic masses of elements in compound. They are the number in red. Add up all of the amu of the atoms in that compound and that is the formula mass. Gas balloon sample: you can determine number of moles of gas w/o knowing the identity because to do this you divvide by the molar volume. The molar volume of a gas at stop is known. It is always 22. 4 l/mol so you don’t need to use a balance. You divide by 22. 4 l/mol. What do the letters VSEPR stand for? Explain what the theory says and ho it is used? VSEPR stands for valance shell electron pair repulsion.
The theory states in compound, electrons arrange themselves as far apart as possible. They arrange themselves geometrically because of the result of the valance e- moving far apart. Describe and explain the trend for atoms within a column of the periodic table: the bond length is how far apart two atoms arei n a covalent bond. As you go down a group the atoms form longer bonds. This is because atoms get larger as you go down a group. Multiple bonds are shorter then single bonds. More electrons in a bond pull the two nuclei closer to each other.