Atoms and elements Flashcards
The area within an atom is mostly filled by ____ ____
Empty space
Where are the protons and neutrons located in an atom?
In the nucleus
How much of the mass of an atom is contained in its nucleus?
99%
The nucleus contains ____% of the mass of the atom
99%
Electrons ____ around the nucleus
Orbit
What charge is carried by protons?
Positive charge
What charge is carried by electrons?
Negative charge
What charge is carried by neutrons?
Neutrons are neutral
Overall, atoms are ____ charged
Neutrally
Why is an atom (generically) neutrally charged?
The number of protons is equal to the number of electrons
What is the name of a charged atom?
An ion
What is an ion?
A charged atom
What is the atomic cloud?
The space occupied by electrons around the nucleus of an atom
What are subatomic particles?
Particles smaller than an atom - protons, neutrons, and electrons
One electron carries what charge?
1-
One proton carries what charge?
1+
One neutron carries what charge?
0
What is the mass of one proton?
1.007
What is the mass of one neutron?
1.008
What is the mass of one electron?
0.00055 (considered to be negligible)
What makes atoms different from each other?
Their atomic mass and their atomic number
What is the atomic mass of an atom?
The sum of all p⁺ and n⁰ in the nucleus
What is given by the sum of all p⁺ and n⁰ in the nucleus of an atom?
The atomic mass
What is the atomic number of an atom?
The number of all p⁺ in the nucleus
What is given by the number of all p⁺ in the nucleus of an atom?
The atomic number
What is the atomic mass of carbon?
6p⁺ : 6n⁰ : 6e⁻ = 12
What is the atomic number of carbon?
6
What is amu?
Atomic mass units; the mass of a proton
What is the meaning of Da in biochemistry?
Daltons, the mass of a proton
Da (used in biochemistry) = amu (used in chemistry
What is the definition of a Dalton?
1/12th of a carbon atom
The more p⁺ or n⁰ you have, the larger the ____ will be
Mass
1 amu = 1 Da = 1 ____
g/mol
1 amu = 1 Da = 1 g/mol
What is an isotope?
An atom with the same number of protons but different number of neutrons
How many protons and neutrons in carbon-12?
Carbon-12 has 6p⁺ and 6n⁰
How many protons and neutrons in carbon-13?
Carbon-13 has 6p⁺ and 7n⁰
How many protons and neutrons in carbon-14?
Carbon-14 has 6p⁺ and 8n⁰
What is the atomic mass of carbon-13?
13 Da
What is the atomic mass of carbon-14?
14 Da
Which is more stable, carbon-12 or carbon-14?
Carbon-12 is more stable than carbon-14
Which is more stable, carbon-13 or carbon-14?
Carbon-13 is more stable than carbon-14
What is an important property of carbon-14?
Carbon-14 is radioactive
Is carbon-13 stable?
Yes, carbon-13 is stable (it accounts for 1.11% of carbon found on earth)
Most elements found on earth are a mixture of ____
Isotopes
If chlorine found on earth is 75.77% chlorine-35 and 24.23% chlorine-37, how do we calculate the true atomic weight of chlorine?
By multiplying the atomic mass of each isotope by their percentage of occurrence before adding them together and finding the average by dividing by 2.
[(35 x 0.7577) + (37 x 0.2423)] / 2 = 35.5 Da
The number after the dash in the name of an isotope (e.g. the ‘14’ in carbon-14) gives what information?
The atomic mass of that isotope
The higher the atomic number, the more ____ could potentially exist
Isotopes
Elements further down the periodic table, i.e. those with higher atomic numbers, are more likely to have a greater number of different ____
Isotopes
What is emitted by unstable isotopes?
Radiation
Name one use of unstable isotopes
Diagnostic imaging (CT-scan)
As the number of protons rises, there are increasingly more ____ than protons
Neutrons
Every element has a different number of ____
Protons
The atomic number tells you how many ____ the atom has
Protons
How many protons does oxygen have?
Oxygen has the atomic number 8, therefore it has 8 protons
How many protons does carbon have?
Carbon has the atomic number 6, therefore it has 6 protons
How many protons does sodium have?
Sodium has the atomic number 11, therefore it has 11 protons
What is the difference beween an atom and an element?
An atom is a singular entity, whereas an element is comprised of multiple atoms of one type
How is molecular mass calculated?
By adding the atomic mass of each atom in the molecule
What is the molecular mass of water? Describe how it’s calculated.
H₂O contains 2 hydrogen and 1 oxygen atoms.
The atomic mass of hydrogen = 1. The atomic mass of oxygen = 16.
Molecular mass = (2x1) + (1x16) = 18 Da
What is Avogadro’s constant (the number)?
6.022x10²³, the number of atoms in one mole of that substance
What is 6.022x10²³ ?
Avogadro’s constant, the number of atoms in one mole of that substance
How many atoms in one mole of a substance?
6.022x10²³
12 eggs in a dozen = ____ atoms in a mole
6.022x10²³
The molar mass of carbon is 12.01. This means that in one mole of carbon there are ____ grams of carbon
12.01
The molar mass of water is 18. This means that in one mole of water there are ____ grams of water.
18
If the molar mass of water is 18 Da, how many molecules of water are in 1mL?
6.022x10²³ x 1/18 = 3.3x10²² molecules of water in one mL
If there are 3.3x10²² molecules of water in 1mL, how many moles of water is in that 1mL?
3.3x10²² / 6.022x10²³ = 0.055 moles
What is the name of the discrete energy levels at which electrons exist?
Quanta
What is required for electrons to populate higher quantised states?
Higher energy
Electrons require higher energy to exist in higher ____ states
Quantised
The ____ atomic model shows the simplified arrangement of electrons in rings around the nucleus
Bohr
The further out from the nucleus an electron is, the more ____ is required
Energy
Electrons reside in ____
Shells
What is the name of the outermost electron shell?
Valence shell
What is the name of the outermost electrons?
Valence electrons
The most important subatomic particles in chemistry are the ____ ____
Valence electrons
Ions are formed by the gain and loss of ____
Electrons
The gain and loss of electrons forms what?
Ions
What is the net charge when an electron is lost?
Net +ve charge
What is the net charge when an electron is gained?
Net -ve charge
Where do electron gains or losses occur?
Within the valence shell
Which electrons are involved in ion formation?
Valence electrons
What are cations?
Ions with a net +ve charge; more protons than electrons
What type of ion has more protons than electrons?
Cation
What type of ion has a net +ve charge?
Cation
What are anions?
Ions with a net -ve charge; more electrons than protons
What type of ion has more electrons than protons?
Anion
What type of ion has a net -ve charge?
Anion
Quantised states are ____ within atoms
Shells
Electron shells contain electron ____
Orbitals
What defines electron filling and configuration?
Electron orbitals
Every electron shell is made up of one or more ____
Orbitals
The number of ____ increases with the number of electron shells
Orbitals
Do orbitals increase in odd or even values?
Odd.
s has 1, p has 3, d has 5, f has 7, etc.
What orbitals are in electron shell 1?
S
What orbitals are in electron shell 2?
An s orbital and a p orbital
What orbitals are in electron shell 3?
An s orbital, a p orbital, and a d orbital
How many orientations does a p orbital have?
Three
How many orientations does a d orbital have?
Five
Which has higher energy, s or p orbitals?
p orbitals
How many electrons can any orbital orientation hold?
A maximum of 2
How many electrons can an s orbital hold?
2 electrons, because s orbitals have one orientation
How many electrons can a p orbital hold?
6 electrons, because p orbitals have 3 orientations
How many electrons can a d orbital hold?
10 electrons, because d orbitals have 5 orientations
What is the filling of orbitals based on?
Energy levels
What does orbital filling determine?
Electron configuration
What is determined by orbital filling and so electron configuration?
Atom reactivity
What determines atom reactivity?
Orbital filling which determines electron configuration
The rows of the periodic table are called ____
Periods
The columns of the periodic table are called ____
Groups
What increases from left to right across the periodic table?
Atomic number and atomic weight
What increases from top to bottom across the periodic table?
Atomic number and atomic weight
The periodic table is grouped in blocks by ____
Orbitals
The periods (rows) of the periodic table show what?
Which electron shell is filling
Electron configuration gave chemists the rationale for what?
How compounds and molecules form
The group (column) an element belongs to in the periodic table tells us what?
How many valence electrons are in the outer shell of that element
Carbon is in group 4 in the periodic table. How many valence electrons does carbon have?
4
Oxygen is in group 6 in the periodic table. How many valence electrons does oxygen have?
6
Electrons are given/taken to obtain stable configuration - what does this mean?
Stable configuration, an electron valency of 8 (full outer shell)
Chlorine is in group 7 of the periodic table. How many valence electrons does chlorine have?
7
The elements in the 8th group of the periodic table have full valency. What does this mean for the properties of these elements?
The elements in the 8th group of the periodic table are very stable and not very reactive
What is the name given to the 8th group of elements on the periodic table?
Noble gases
What is electronegativity?
An atom’s attraction for other electrons (to make a chemical bond)
Do atoms with higher values of electronegativity generally lose, share, or gain electrons?
Gain
Do atoms with low values of electronegativity generally lose, share, or gain electrons?
Lose
Do atoms with middle values of electronegativity generally lose, share, or gain electrons?
Share
Essentially, an atom’s electronegativity is its desire to become what?
A noble gas
Elements in groups 1, 2, and 3 tend to become ____ (ion type)
Cations
Elements in groups 5, 6, and 7 tend to become ____ (ion type)
Anions
Elements in groups 1, 2, and 3 tend to become cations by ____ their electrons
Losing
Elements in groups 5, 6, and 7 tend to become anions by ____ their electrons
Gaining
When Na bonds with Cl₂, which element loses electrons?
Na is in group 1 of the periodic table - Na loses one electron, becomes a cation
When Na bonds with Cl₂, which element gains electrons?
Cl is in group 7 of the periodic table - Cl gains one electron, becomes an anion
