Review of Chemistry I

Review of Chemistry I

types of bonds

balancing equations

electron configurations

moles

Two types of bonds:

• Covalent bonds

• Ionic bonds

Covalent bonds

• the bond between two nonmetals

• sharing of electrons

•  $H_2O$  

• Can have single(2 electrons are shared between two atoms), double(4 electrons are shared between two atoms), or triple(6 electrons are shared between two atoms) bonds

• double bond -  $CO_2$  

• triple bond -  $N_2$  

Ionic Bonds

• transfer of electrons

• between nonmetals & metals

• NaCl

• ion - atom loses or gains gains an electron

•  $Na^+Cl^-$  

Multiple Choice

Salt is an example of what?

• ionic compound

• covalent compound

Multiple Choice

Water is an example of what?

• molecular compound (covalent compound)

• ionic compound

Multiple Choice

Electrons are involved in chemical reactions, not protons or neutrons.

• true

• false

Multiple Choice

How are ionic bonds formed?

• transfer of electrons

• sharing of electrons

Multiple Choice

Atoms are most stable when their outer shell is full or complete.

• true

• false

Multiple Choice

Ionic bonds are between

• metals and nonmetals

• 2 metals

• 2 nonmetals

Multiple Choice

When an atom loses an electron, it becomes a

• positive ion

• negative ion

Multiple Choice

What two types of atoms make a covalent bond?

• 2 nonmetals

• 2 metals

• 1 metal and 1 nonmetal`

Multiple Choice

How do covalent bonds form?

• by sharing electrons between atoms

• by donating or receiving electrons

Multiple Choice

Valence electrons are found

• outermost energy level

• innermost energy level

• some where in the electron cloud

Multiple Choice

Valence electrons are found

• outermost energy level

• innermost energy level

• some where in the electron cloud

Balancing Equations

•  $H_2\ +\ O_2\ ->\ H_2O$  

•  $2H_2\ +\ O_2\ ->\ 2H_2O$  

Multiple Choice

 $Al\ +\ Fe_2O_3\ ->\ Fe\ +\ Al_2O_3$  

Balance the equation:

•  $Al\ +\ Fe_2O_3\ ->\ 2Fe\ +\ Al_2O_3$  

•  $2Al\ +\ Fe_2O_3\ ->\ 2Fe\ +\ Al_2O_3$  

•  $2Al\ +\ Fe_2O_3\ ->\ Fe\ +\ Al_2O_3$  

• already balanced

Multiple Choice

Balance the equation:   $CS_2\ +\ Cl_2\ ->\ CCl_4\ +\ S_2Cl_2$  

•  $CS_2\ +\ 3Cl_2\ ->\ CCl_4\ +\ S_2Cl_2$  

•  $3CS_2\ +\ Cl_2\ ->\ CCl_4\ +\ S_2Cl_2$  

• already balanced

Multiple Choice

Balance the equation:   $NO_2\ +\ O_3\ ->\ N_2O_5\ +\ O_2$  

•  $NO_2\ +\ 2O_3\ ->\ N_2O_5\ +\ O_2$  

•  $2NO_2\ +\ O_3\ ->\ N_2O_5\ +\ O_2$  

• already balanced

Electron Configuration

• Electrons occupy energy levels by filling the lowest level first and continuing to higher energy levels

Multiple Choice

Which element corresponds to the following electron configuration:

 $\left[He\right]2s^22p^4$  

• C

• N

• O

• F

Multiple Choice

Which element corresponds to the following electron configuration?

 $\left[Ne\right]\ 3s^23p^4$  

• Si

• P

• S

• Cl

Multiple Choice

Within the energy levels around the nucleus, sublevels can be find. The energy sublevels are designated as:

• s,p,d,f

• 2,8,16

• orbitals

Multiple Choice

Within the energy levels around the nucleus, sublevels can be find. The energy sublevels are designated as:

• s,p,d,f

• 2,8,16

• orbitals

Stoichiometry

finding the number of particles to a mass by using dimensional analysis with moles

Moles/ Avogadro's number(constant)

Atoms are so tiny that an ordinary-sized sample of substance contains so many of these submicroscopic particles that counting them by grouping them in thousands would be unmanageable.

Hydrogen

atomic weight - 1.008

one H atom = 1.008 amu

weight of 1 mole of H atoms is 1.008 grams

One mole

 $6.023\ x\ 10^{23}$  particles

Multiple Choice

One mole of the element lead (Pb) contains ________ atoms and weights _________.

• $6.023\ x10^{23}$ atoms & 207.2 g

• 207.2 atoms & $6.023\ x10^{23}$ g

• 207.2 atoms & 207.2 g

• $6.023\ x10^{23}$

Multiple Choice

How many atoms of carbon and sulfur are needed to make one molecule of carbon disulfide?

 $CS_2$  

• two atoms of S; one atom of C

• one atom of C; two atoms of S

• one atom of C; one atom of S

• two atoms of C; two atoms of S

Multiple Choice

To make one mole of carbon disulfide molecules requires how many moles of carbon atoms and sulfur atoms?

• 1 mole of C; 1 mole of S

• 2 moles of C; 1 mole of S

• 1 mole of C; 2 moles of S

Molar Mass

molecular mass = molecular weight = formula mass = formula weight
unit - grams/mole

 $SO_2$  
1 S atom - weighs 32.07 g; 2 oxygen atoms - weigh (2x15.99) 31.98 g
molar mass - 32.07g + 31.98g = 64.05 g/mol
1 mole of sulfur dioxide molecules weights 64.07g

Practice molar mass:

 $Cl_2$  
KOH
Answers:
71 g/mol
56.1 g/mole

Multiple Choice

What is the molar mass of

 $FeCl_3$  

• 55.845 g/mol

• 162.2 g/mol

• 106.359 g/mol

Multiple Choice

What is the molar mass of

 $Mg\left(OH\right)_2$  

• 36.012 g/mol

• 58.3 g/mol

• 24.305 g/mol

Using molar mass as a conversion factor

How many moles of lithium are in 25g of lithium?

molar mass - 6.94 g/mol

3.6 mol Li

What is the mass of 11.5 moles of lithium?

79.8 g Li