UNIT 1:
MEASUREMENT AND DATA PROCESSING
MEASUREMENT AND DATA PROCESSING
A series of measurements of a table’s length yields the following results:
150.1 cm
150.2 cm
150.0 cm
Describe the result if the actual length of the table is 152 cm.
Precise, not Accurate
Identify the property that does not belong to the category of extensive properties.
Mass, Volume, Density, Heat Capacity
Density
Atomic number
This subatomic particle plays a crucial role in determining an element's chemical properties and reactivity.
Valence electron
This fundamental principle states that in a chemical reaction, the total mass of the reactants must equal the total mass of the products, which is essential for balancing chemical equations.
A type of error that occurs due to unpredictable fluctuations in measurement processes.
Random Error
Method used to separate salt and water solution.
Evaporation
Differentiate ions and isotopes.
Ions = charged, unequal no. of protons and electrons
Isotopes = same element and no. of protons, different number of neutrons
The energy required to remove an electron from an atom in its gaseous state.
Ionization energy
Balance the chemical equation: C3H8+O2→CO2+H2O
C3H8+5O2→3CO2+4H2O
A student measures the length of a pencil with a ruler and finds that it is between 7.4 cm and 7.5 cm, with the closest line marking at 7.45 cm. Considering the uncertainty in the measurement, state the best estimate of the pencil's length.
7.45 cm ± 0.05 cm
A combination of two or more substances that are not chemically bonded and can be separated by physical means
The weighted average mass of an atom of an element compared to one-twelfth the mass of a carbon-12 atom.
State the trend of effective nuclear charge (Zeff) and electron shielding across the periodic table.
Zeff = increases (number of protons in the nucleus increases)
Shielding = remains constant (number of inner shell electrons remains the same)
Calculate the molar mass of ethanol (C2H5OH).
46.07 g mol-1
An electronic balance has a "tare" on it. The reading of balance is reset to zero when the tare button is pressed. State a reason why use of the tare button improves the measurement.
Reduces/eliminates systematic error
State two characteristics of a homogenous mixture.
Uniform composition/Single phase/Does not settle
Give the complete set of quantum numbers for 4f3.
n=4, l=3, ml=-1, ms=+1/2
State and explain the trend for chemical reactivity for Group 1 and Group 17 elements down a group in the periodic table.
Group 1 - increases (increasing atomic size and decreasing ionization energy make it easier to lose the outermost electron)
Group 17 - decreases (increasing atomic size and decreasing electronegativity reduce the ability to gain an electron)
Calculate the number of moles in 25.0 grams of ethanol C2H5OH (M = 46.07 g/mol)
n=m/M
=0.543 moles
A substance has a mass of 15.00 g and occupies a volume of 5.0 cm3. Calculate the density of the substance.
3.0 g cm-3
This describes how matter is made up of small particles in constant motion, explaining the differences in properties of solids, liquids, and gases.
Kinetic Particle Theory
Identify and explain the rules for filling electrons in orbitals.
Aufbau Principle - electrons occupy the lowest energy orbitals first before filling higher energy orbitals.
Hund's Rule: for orbitals with the same energy, electrons will occupy each orbital singly before pairing up in the same orbital.
Pauli Exclusion Principle: No two electrons in an atom can have the same set of four quantum numbers.
State and explain the trends in atomic radius down the 2nd group and across the 4th period.
Group 2 - increases (increased shielding effect)
Period 4 - decreases (increasing nuclear charge, constant electron shielding)
Calculate the mass in grams of 5.90 moles of ethanol, C2H5OH (molar mass = 46.07 g/mol)
m=n×M
= 272 g