Classification of Matter
Which elements form diatomic elements in nature?
H O F Br I N Cl
0.006024 has how many sigfigs?
4
Ca2+ has how many electrons?
18
What is the formula for: calcium nitride?
What is Ca3N2?
A compound AB contains 40.0 g of A and 60.0 g of B. What mass of B is present in a 150.0 g sample of AB?
90.0 g
In a neutral atom, the number of protons must equal the number of
Whare are electrons?
Perform the calculation and round correctly: 2.50 L − 0.086 L
4.14 L
How many electrons, protons, and neutrons does an atom of strontium-90 contain?
38 electrons
38 protons
52 neutrons
Write the formula for dinitrogen pentasulfide.
N2S5
An element X has a naturally occurring atomic mass of 11.3 u and two isotopes: 8X and 12X. What is the percentage of 12X in nature? (Assume masses of 8.00 u and 12.0 u for the isotopes)
82.5 %
Which is a main group elememt?
a. Pu
b. Mg
c. Sc
d. Fe
Mg
A rectangular metal block measures 2.0 cm × 3.0 cm × 4.0 cm and has a density of 8.90 g/cm³. What is the mass of the block?
214 g
How many protons, neutrons, and electrons are in 31P3-?
15 protons
18 electrons
16 neutrons
The chemical name for the compound PbSO4
What is lead(II) sulfate?
Element X has two isotopes: X-30 (mass=30.0 u), X-34 (mass=34.0 u)
The average atomic mass is 33.2 u. What percent is Q-34?
80%
Ions are made in what way?
Losing or gaining electrons?
A compound XY weighs 33.32 g and contains 10.25 g of element X. How many grams of element Y are in a second 20.00 g sample of XY?
13.85 g
Which ion has twenty-six electrons?
a. Cr2+
b. Fe2+
c. Ni2+
d. Cu2+
Ni2+
Magnesium forms an ionic compound with an element with the formula MgX. Which ion could be X?
a) Br-
b) P3-
c) C4-
d) S2-
d) S2-
Suppose an element has three naturally occurring isotopes. Isotope 1 has 2.00% abundance and mass 22.488 amu. Isotope 2 has 95.00 % abundance and mass 23.581 amu. Isotope 3 has mass 24.490 amu. What is the atomic mass for the element?
23.586 amu
Identify each as molecular or ionic:
1. P₂O₅
2. Rb₂S
3. Cl₂O₇
4. MgBr₂
1. molecular
2. ionic
3. molecular
4. ionic
Convert 96 in2 to ft2
0.667 ft2
Which pair of particles has the same number of electrons?
a. F-, Mg2+
b. Ne, Ar
c. Br-, Se
d. Al3+, P3-
a. F-, Mg2+
What is the name of this acid? HNO2
nitrous acid
Lithium has two naturally naturally occurring isitopes, 6Li and 7Li, with masses of 6.015 amu and 7.016 amu, respectively. What is the relative abundance of each isotope?
6Li = 7.49 % and 7Li = 92.51 %