Chemistry Midterm
Physical means can be used to separate
mixtures
Compared with nonmetals, the number of valence electrons in metals is generally
smaller
Under ordinary conditions of temperature and pressure, the particles in a gas are
very far from eachother
Particles within a solid
vibrate weakly about fixed positions.
he state of matter in which a material has a definite volume but no definite shape is the
liquid state
If electromagnetic radiation A has a lower frequency than electromagnetic radiation B, then compared to B the wavelength of A is
longer
Light travels at a speed of 3.00 x 1010cm/s. What is the speed of light in kilometers/hour?
1.08 x 10° km/h
Group in the periodic table contains only metals.
2a
The electron configuration of nitrogen is 1s22s22p3. How many more electrons does nitrogen need to satisfy the octet rule
3
What is the number of significant figures in the measurement 5.00 cubic meters?
3
A sample of element X contains 90 percent35X atoms, 8.0 percent 37X atoms, and 2.0 percent 38X atoms. The average atomic mass is closest to
35 amu
if 75.0% of the atoms of an element each have a mass of 35.0amu, and 25.0% of the atoms each have a mass of 37.0 amu, what is the average atomic mass of the element?
35.5 amu
In the electron configuration for scandium (atomic number 21), what is the notation for the three highest-energy electrons?
3d14s2
hat is the number 0.0513 expressed in scientific notation?
5.13x 10-2
Which of these observations or values represents an extensive property of the material? a. Liquid b. 3.01 g/cm c. 500 cm d. Pale green
500 cm
The number of electrons in the highest energy level of the argon atom (atomic number 18) is
8
What is the volume of a paperback book 21 cm tall, 12 cm wide, and 3.5 cm thick?
8.8 x 102cm3
Zoe observes water bubbling. She measures the temperature of the water to be 373 K. Is she most likely observing a chemical or physical change?
A physical change because 373 K is the boiling point of water
Which statement describes a physical change? a. An iron bolt on a bridge rusts and weakens the bridge. b. The surface of a silver cup turns black when it is exposed to air. c. A sculptor casts a statue in molten bronze and allows it to harden. d. Slivers of magnesium in fireworks form a bright glow as they burn.
A sculptor casts a statue in molten bronze and allows it to harden.
Why do all samples of a given substance have the same intensive properties?
All the samples have the same chemical composition.
Which concept in Dalton's atomic theory has been modified? a. All matter is composed of atoms. b. Atoms of different elements have different properties and masses. c. Atoms can combine in chemical reactions. d. Atoms cannot be divided.
Atoms cannot be divided.
How are compounds different from elements?
Compounds can be broken apart by chemical means into simpler substances, but elements cannot.
Which two categories are used to classify properties of matter?
Intensive and extensive
Is the freezing of mercury a reversible or irreversible physical change? Why?
It is reversible because solid mercury can be melted to form liquid mercury again.
Upon completion of a laboratory investigation, where should students return the materials?
Materials should be returned to the designated location
Which is an acceptable way to protect your eyes in the chemistry laboratory?
Only by wearing chemical safety goggles
Which are the chemical symbols for lead, oxygen, and silver, in that order?
Pb, 0, Ag
A chemist mixes liquid Substance X and solid Substance Y in a beaker, then stirs the mixture vigorously. Which observation or measurement would provide the strongest evidence that the two substances have undergone a physical change, but not a chemical change?
The mixture can be separated into two substances, one with the same melting point as Substance X and the other with the same melting point as Substance Y.
Which of the following is NOT part of Dalton's atomic theory? a. Atoms cannot be divided, created, or destroyed. b. The number of protons in an atom is its atomic number. c. In chemical reactions, atoms are combined, separated, or rearranged. d. All matter is composed of extremely small particles called atoms.
The number of protons in an atom is its atomic number.
What causes the high density of solids?
The particles are packed closely together.
Which equals the speed of a wave?
The product of wavelength and frequency
How does visible light differ from radio waves, microwaves, and the other components of the electromagnetic spectrum?
Visible light has a different range of frequencies and wavelengths.
A measurement that closely agrees with accepted values is said to be
accurate
A measurement is said to have good precision if it
agrees closely with other measurements of the same quantity.
The group of soft, silvery active metals, all of which have one electron in an s orbital, is known as the
alkali metals.
The most characteristic property of the noble gases is that they
are largely unreactive.
Poor precision in scientific measurement may arise from
both human error and the limitations of the measuring instrument.
he electrostatic attraction between positively charged nuclei and negatively charged electrons permits two atoms to be held together by a(n)
chemical bond
Precision pertains to all of the following EXCEPT a. reproducibility of measurements. b. agreement among numerical values. c. sameness of measurements. d. closeness of a measurement to an accepted value.
closeness of a measurement to an accepted value.
Which of the following is an intensive physical property? a. volume c. color b. length d. mass
color
he principles of atomic theory recognized today were conceived by
dalton
Which of the following is a physical property of a substance in the liquid state?
definite volume
Experiments with cathode rays led to the discovery of the
electron.
The change of an atom from an excited state to the ground state always requires
emission of electromagnetic radiation.
Which of the following is a physical change?
evaporation
One of the wave properties of electromagnetic radiation, such as light, is
frequency
cross a period in the periodic table, atomic radii
gradually decrease.
Which groups in the main group have lower electronegativity than d-block elements?
groups 1 and 2
Hydrogen is placed separately from other elements in the periodic table because it
has many unique properties.
In the alkaline-earth group, atoms with the smallest radii
have the highest ionization energies
chemical properties
include changes that alter the identity of a substance.
As the atomic number increases, the number of electrons in an atom
increases
Helium-4 and helium-3 are
isotopes
Matter includes all of the following EXCEPT a. air. c. smoke. b. light. d. water vapor.
light
The compressibility of solids is generally
lower than the compressibility of liquids and gases
What is the symbol and meaning of the prefix milli-?
m; 10-3
An example of an extensive physical property is
mass
Two features that distinguish matter are
mass and volume.
Atoms of the same element can differ in
mass number
Isotopes are atoms of the same element that have different
masses
physical prope may be investigated by
melting ice
The elements that border the zigzag line in the periodic table are
metalloids
Compared with the particles in a gas, the particles in a liquid
move around less.
The average atomic mass of an element is the average of the atomic masses of its
naturally occurring isotopes.
A student making a serial dilution of hydrochloric acid spills a small amount of the acid on the lab table. Which of the following should the student do first?
notify his/her lab partner and tell the teacher
The periodic law states that the physical and chemical properties of elements are periodic functions of their atomic
numbers
Mendeleev's table was called periodic because the properties of the elements
occurred at repeated intervals called periods
If the s and p orbitals of the highest main energy level of an atom are filled with electrons, the atom has a(n)
octet
The electron configurations of the noble gases from neon to radon in the periodic table end with filled
p orbitals.
A horizontal row of the periodic table is usually referred to as a
period
Mendeleev is credited with developing the first successful
periodic table
Using the same balance, a chemist obtained the values 5.224 g, 5.235 g, and 5.25 g for the mass of a sample. These measurements have
poor precision
These values were obtained as the mass of products from the same reaction: 8.83 g; 8.84 g; 8.82 g. The known mass of products from that reaction is 8.60 g. The values are
precise
A chemist who frequently carries out a complex experiment is likely to have high
precision
Which of these entries in the table refers to a chemical property of methanol? a. Boiling point b. Color c. Products of combustion d. specific gravity
products of combustion
Elements in a group or column in the periodic table can be expected to have similar
properties
One chemical property of matter is
reactivity
The average atomic mass of an element depends on both the masses of its isotopes and each isotope's
relative abundance.
In Group 2A elements, the valence electrons are in sublevel
s
The state of matter in which particles are rigidly held in fixed positions is the
solid state
What are the three main states of matter?
solid, liquid, gas
The substances that are chemically bound together are
the elements that compose water.
Isotopes of each element differ in
the number of neutrons in the nucleus.
line spectrum is produced when an electron moves from one energy level
to a lower energy level
The attractive forces in a liquid are
too weak to hold the particles in fixed positions.
Which is NOT a property of metals? a. malleability c. unreactivity b. ability to conduct heat and electricity d. ductile
unreactivity
A list of pure substances could include
vitamin C (ascorbic acid).
The distance between two successive peaks on a wave is its
wavelength
In Rutherford's experiments, positively charged particles
were used to bombard thin metal foil.
Compared with gases, solids are
incompressible