Intro to Chem & Matter
Temperature remains constant.
What is the relationship between cesium-133 and cesium-135, and how many neutrons does each atom have?
isotopes, 133-55=78, 135-55=80
What is the relationship between wavelength, frequency, and energy?
Wavelength increases as frequency decreases.
Wavelength increases as energy decreases.
Frequency increases as energy increases.
Which is not always true?
a. An element with 1 valence electron is an alkali metal.
b. The halogens are the most reactive nonmetals.
c. An alkaline earth metal has two valence electrons.
d. A noble gas has a full valence shell.
a. hydrogen has one valence electron and is a nonmetal
Identify each as ionic or covalent/molecular.
a. H2O
b. NH4ClO
c. CaCl2
a. covalent
b. ionic
c. ionic
Which is false?
a. A precipitate is a solid that forms when two liquids react.
b. Malleability is a liquid's resistance to flow.
c. Phase changes are physical changes.
d. A chemical change changes the identity of a substance.
B
What is the charge of an atom's nucleus?
positive charge equal to atomic number
Define principal quantum number.
tells the energy level; the 3 in 3s2 for example
Define atomic radius, ionization energy, and electronegativity.
atomic radius - size of an atom
ionization energy - the energy it takes to remove an electron
electronegativity- the ability of an atom to pull electrons towards itself in a chemical bond
Ionic compounds form through the __ of electrons, which covalent compounds form through the __ of electrons.
transfer; sharing
True or false?
Sublimation is a chemical change.
False
The half-life of radium-226 is 1600 years. How many grams of a 0.25g sample will remain after 480 years?
0.20 g
What determines the color of light seen in an element's bright line spectrum?
What is the relationship between atomic radius, ionization energy, and electronegativity?
As atomic radius increases, ionization energy and electronegativity decrease. The atom has a weaker pull on the valence electrons as they get farther from the nucleus.
How many atoms of each element are present in aluminum acetate?
Al(C2H3O2)3
Al-1, C-6, H-9, O-6
List the metric prefixes with their abbreviations and numerical values.
kilo, k, 1000; hecto, h, 100; deka, da, 10; base, (g, m, L, s), 1; deci, d, 0.1; centi, c, 0.01; milli, m, 0.001
Write an equation describing an atom of uranium-238 that undergoes alpha decay.
23892U -> 42He + 23490Th
A microwave has a wavelength of 7.6 x 10-2 m. What is its frequency?
3.9 x 109 1/s or Hz
Explain the trend for atomic radius, including ions.
Atomic radius increases from top to bottom on the periodic table because energy levels are added. Atomic radius decreases from left to right because adding protons in the nucleus pulls in electrons. Atomic radius is smaller for cations because they have lost electrons and bigger for anions because they have gained electrons.
The formulas of ionic compounds must be __, but not the formulas of covalent compounds.
The names of covalent compounds use __, but not the names of ionic compounds.
simplified; prefixes
Which is incorrect?
a. 92 cm3= 92mL b. 21 hL = 2.1 kL c. 39.7 mm = 39700 dm d. 18 das = 180 s
C
Describe fission and fusion, including where they take place.
During fission, a large atom breaks apart into smaller pieces after being hit with a neutron. This reaction is used in nuclear power plants. During fusion, two small atoms fuse to form a bigger atom. This occurs in the sun and other stars.
Write the longhand electron configurations for Cu, Cu+1, and Cu+2.
Cu: 1s22s22p63s23p64s13d10
Cu+1: 1s22s22p63s23p63d10
Cu+2: 1s22s22p63s23p63d9
Which is false?
a. K has a larger radius than K+1.
b. F is the most electronegative element.
c. Ca is larger than As.
d. Al has a higher ionization energy than Al+3.
D- Ionization energy is higher for cations. Since they are smaller than neutral atoms, the valence electrons are closer to the nucleus, meaning they are harder to remove.
Which is false?
a. Magnesium hypochlorite is MgClO2
b. Heptahydrogen disulfide is H7S2
c. Aluminum phosphide is AlP
d. Lithium phosphate is Li3PO4
a. Magnesium hypochlorite is Mg(ClO)2