Semester 2 Exam Year 11 Flashcards
Who created the Periodic table and when?
Dmitri Mendeleev in 1869.
What are columns and rows called in the Periodic table?
Columns – Groups, Rows – Periods
In what order are elements placed in the Periodic table?
Order is based on their atomic number
In a neutral atom, the number of electrons will equal…?
The number of protons
The number of valence electrons is the same within…?
A column
The number of valence electrons increase…?
Left to right within a row
What are elements represented by?
Symbols
What makes up an atom?
It consists of a nucleus made up of protons and neutrons (nucleons) and an electron cloud where electrons are located.
What is the atomic number?
The number of protons.
What is the mass number?
The mass number is how heavy an atom is. It consists of the number of protons and neutrons in the nucleus.
What is the electron configuration?
The number of shells containing electrons and the number of electrons in each shell.
How many electrons can fit in the first shell?
2 electrons.
How many electrons can fit in the second and third shells?
8 electrons.
How many electrons can fit in the fourth shell?
32 electrons.
What are valence electrons?
The valence electrons of an atom are the electrons located in the highest occupied principal energy level.
What are valence electrons responsible for?
Valence electrons are primarily responsible for the chemical properties of elements.
What is the octet rule?
The octet rule states that atoms tend to form compounds in ways that give them eight valence electrons and thus the electron configuration of a noble gas.
What is the exception to the octet rule?
the first noble gas, helium, which only has two valence electrons.
What are the two ways atoms can satisfy the octet rule?
sharing their valence electrons and transferring valence electrons from one atom to another.
Atoms of metals tend to __ all of their valence electrons, which leaves them with an octet from the next lowest principal energy level.
lose
Atoms of nonmetals tend to __ electrons in order to fill their outermost principal energy level with an octet.
gain
Atoms of nonmetals tend to __ electrons in order to fill their outermost principal energy level with an octet.
gain
What is the atomic radius trend?
Atoms from right to left increase in atomic radius. Atoms from top to bottom also increase in atomic radius. This is because the atomic radius generally decreases as you move from left to right across a period (due to increasing nuclear charge) and increases as you move down a group (due to the increasing number of electron shells).
What is the valence trend?
In a period, the number of valence electrons increases as we move from left to right side. However, in a group this periodic trend is constant, that is the number of valence electrons remains the same.
What is the first ionisation energy trend?
First ionisation energy of an element measures the minimum amount of energy needed to remove the single electron from an atom. It increases going up a group and left to right.
What is ionisation energy?
An element’s ionisation energy is a measure of how strongly it holds onto its electrons.
What is the electronegativity trend?
Electronegativity is the ability of an atom in a molecule to attract electrons to itself. Non-metals have the highest values of electronegativity. It increases from left to right in a period and decreases down a group.
What are isotopes?
Isotopes are atoms of an element with the same number of protons but different numbers of neutrons. Different isotopes of the same element have the same chemical properties but different physical properties.
What is the relative atomic mass?
The average mass of its atoms, compared to 1/12 of the mass of a carbon atom.
What is the formula for relative atomic mass?
A(relative) = total mass of atoms / total number of atoms
How do you calculate formula mass?
Adding up the atomic masses of the elements involved.
What is the units for formula mass?
gmol^-1
What is atomic absorption spectrometry?
A technique that is used to determine the concentration of different elements in solution.
How does atomic absorption spectrometry work?
By focusing light of a specific wavelength on atoms and measuring how much light was absorbed.
What is absorbance?
The measurement of light that is absorbed by a substance.
What happens when an electron absorbs energy?
When an atom absorbs energy, electrons may move from a lower energy level to higher one. Once they have reached a higher level, they drop back down to a lower one. When this happens, the atom emits light. Atoms of different elements absorb and emit certain wavelengths.
What is an absorption spectrum?
An absorption spectrum shows what happens when an atom absorbs certain frequencies of light. The dark stripes represent the light that is absorbed.
What is an emission spectrum?
An emission spectrum shows the frequencies of light that are emitted.
What is mass spectrometry?
An analytical technique where ions are sorted on their mass to charge ratio.
How can mass spectrometry be used quantitively?
Determining the concentration of solution
How can mass spectrometry be used qualitatively?
Identifying elements in a solution.
What does a mass spectrometer produce?
A mass spectrum.
What is a mass spectrum?
A chart that shows the composition of a solution. The components are shown in order of mass to charge ratio. The composition is shown as percent abundance.
What are the four steps to how a mass spectrometer work?
- vaporisation
- ionisation
- acceleration and deflection
- detection
What is a pure substance?
Pure substances are substances that have a fixed or constant composition and cannot be separated into other substances by physical means.They can either be elements or compounds.
what are the two types of mixtures?
homogenous and heterogenous.
What is a homogenous mixture?
A mixture that is uniform in composition
What is a heterogenous mixture?
A mixture that is not uniform in composition.
What is sieving?
Involves separating a mixture based on particle size. The material that makes it through is called the negative fraction. The material that does not make it through is called the positive fraction.
What is filtration and evaporation?
Filtration involves separating solid particles from a solution. Evaporation is drying or heating a solution to separate the solute from the solvent.
What is distillation?
Involves separating components based on their boiling points.