Matter Properties and Changes + The Structure of an Atom
What is an atom composed of, and what are their charges?
protons (+), neutrons (n), and electrons (-)
What are the trends that can be observed throughout the periodic table?
Across a period:
1. atomic radius decreases
2. ionization energy increases
3. electronegativity increases
4. reactivity decreases
Down a period:
1. atomic radius increases
2. ionization energy decreases
3. electronegativity decreases
4. reactivity increases
How do we name and write chemical formulas for ionic compounds?
(Know that ionic compounds transfer electrons between metals and nonmetals)
a. nonmetals end with the suffix ide
b. 1st element is always a metal + keeps its name
to write the formula: first, write out the elements that you will be working with, next in the periodic table look for their oxidation state and write the element's symbol and charge for both atoms. Then the charges will "criss-cross". If the two elements have the absolute values of their charges, the compound will be neutral.
Lithium Nitrogen
Li+1 N-3
Lithium Nitride
Li3N
What are the products and reactants in the following equation?
calcium carbonate decomposes and produces calcium oxide and carbon dioxide
a. reactants
calcium carbonate (CaCO3 (s))
b. products
calcium oxide (CaO)
carbon dioxide (CO2)
Boron has two isotopes B-10 which has an abundance of 19.8% and a mass of 10.013, while isotope B-11 has an abundance of 80.2% and a mass of 11.009. What is boron's atomic mass?
10.81 amu
True or False: Air is a homogeneous mixture?
True
The outermost electrons that determine an atom's properties. Elements in the same group have similar chemical characteristics due to the same number and correspond to the group where the elements are located in the periodic table.
What are valence electrons?
What are the three types of bonds that can exist within three of the seven diatomic particles? What are the three elements? How many electrons do the bonds represent?
a. single, double, and triple bond
b. hydrogen is single, oxygen is double, and nitrogen is triple
c. single represents 2, double represents 4, and triple represents 6
What is the best way to balance chemical equations?
Add coefficients so that the reactants and products are equivalent on both sides of the arrow. Never get rid of subscripts or add subscripts.
Gadolinium atom has an atomic number of 64, a mass of 153, how many neutrons does it have?
153 - 64 = 89
What determines the abundance of an isotope?
What is the atomic mass is closer to the isotope number. For example, Nitrogen has isotopes N-14 and N-15. The atomic mass of Nitrogen is 14.007 can be rounded to 14 as a whole number. Therefore, isotope N-14 is more abundant than isotope N-15?
What is created when metals lose valence electrons and when nonmetals gain valence electrons?
Cations are derived from metals. They are smaller, positive ions of the neutral charge of an atom. Anions are derived from nonmetals. They are bigger, negative ions of the neutral charge of an atom.
Metals Non metals
- fewer valence electrons - more valence electrons
(1,2,3) (5,6,7)
*the charge is known as the oxidation state of an element
What is electron negativity difference?
Electronegativity describes the degree to which an atom attracts electrons in a chemical bond. The difference in the electronegativity of two atoms determines their bond type.
a. the difference is more than 1.7, the bond is ionic
b. the difference is between 0.4 and 1.7, the bond is polar covalent
c. the difference is less than 0.4, the bond will have a nonpolar covalent character.
What are the different types of chemical reactions?
a. synthesis
b. single replacement
c. double replacement
d. combustion
e. decomposition
What element can be found in group 18, period 2, block p?
Neon
Are phase changes considered physical changes, why or why not?
No, because heat is not being added or eliminated from the reaction. A property that pertains to a phase change is that they are irreversible and no new products can be formed.
What are the seven diatomic elements?
H2, N2, O2, F2, Cl2, Br2, I2
What is the VSEPR Theory?
Based on the arrangement that minimizes the repulsion of shared and unshared pairs of electrons around the central atom. Used to predict the geometry of individual molecules from the number of electron pairs surrounding their central atoms.
a. linear
b. trigonal planar
c. tetrahedral
d. trigonal pyramidal
e. bent
Balance the following equation and state the remaining states of matter:
Na2S (aq) + Cd(NO3) (aq) -> CdS () + NaNO3 ()
Na2S (aq) + Cd(NO3) (aq) -> CdS (s) + 2NaNO3 (aq)
Barium has an electron configuration of:
2-8-18-18-8-2
Will it lose or gain electrons? How many?
Loses two electrons
Copper has two isotopes Cu-63 which has an abundance of 69.2% and a mass of 62. 930, while isotope Cu-65 has an abundance of 30.8% and a mass of 64.928. What is copper's atomic mass?
63.55 amu
If Na (sodium) has an electron configuration of 2-8-1, why would the atom lose the one electron in its outermost shell? What would its electron configuration then become?
The atom loses one electron, so the number of valence electrons coincides with having all orbital shells full to their maximum potential. The configuration would then become 2-2-6-1.
What are some characteristics of covalent compounds?
a. soft
b. non-conductors of heat and electricity
c. low melting point
d. crystalline structure
Is there a reaction taking place? Why or why not?
Cu + H2O -->
No, because Cu is less active than H2 as shown in Table J on the reference table.
Determine the electronegativity difference and bond type between Na and S
Na = .93
S = 2.58
2.58 - .93 = 1.65
Bond is polar covalent