Chapter 2: Elements and The Periodic Table Flashcards
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ATOM
The building blocks of all matter.
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What is each atom made up of and what are those components, collectively called?
Each atom is made up neutrons, electrons, and protons. These particles are known as subatomic particles.
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What is a neutron in the context of the atom?
A neutron is simply a neutrally charged subatomic particle which is found from subtracting the mass number from the atomic number.
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What is an ION?
An ion is a atom that has lost or gained one or more electrons.
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Where does the majority of the atom’s weight come from?
It comes from the nucleus, which contains the neutrons and protons.
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Electrons have barely any_____?
weight.
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What are electrons held together by?
They are held together by the electrostatic force of attraction.
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What is the electrostatic force of repulsion?
It is the repelling of the chrages.
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What are isotopes?
They are atoms that have the same number of protons but different number of neutrons.
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Why do ion atoms lose their electrons?
They do this inorder to become stable and for larger atoms, it is to satisfy the OCTET RULE.
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What are CATIONS and ANIONS?
CATIONS are atoms that lose electrons and are positively charged. They have more protons than electrons.
ANIONS are atoms that gain electrons and are negatively charged. They have more electrons than protons.
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Protons are positively charged so why do they not repel each other?
Even though they are positively charged, they don’t repel each other because they’re held by NUCLEAR FORCES which are stronger than the ELECTROSTATIC FORCE OF ATTRACTION.
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Carbon Isotope No. of neutrons Formula:
number of neutrons = atomic mass - atomic number.
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When do IONS form?
Ions form when atoms either gain or lose electrons and no longer have the same number of protons and electrons.
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______ form CATIONS?
Metals.
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______ form ANIONS?
Non-metals.
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Bohr Model Vs. Schrödinger Model
BOHR
* major shells
- all electrons follow an orbital pathway
- electrons are arranged in pairs
- each shell has a different energy level
SCHRODINGER
* major shells are divided into subshells and orbital
- electrons follow different pathways depending on what subshell they are in
- electrons arranged in pairs
- each subshell has a different energy level
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Ground State
The ground state configuration is the lowest energy, most stable arrangement.
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Excited State
An excited state configuration is a higher energy arrangement (it requires energy input to create an excited state).
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Horizontal rows on the periodic table represent and what do they tell you?
Periods; (1-7)
Periods tell us how many shells it has.
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Vertical columns on the periodic table represent and what do they tell you?
Groups; (1-18) or (1- 8A/B)
Groups tell us how many valence electrons there are.
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What are critical elements?
Critical elements are elements that are endangered.
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Examples of critical elements?
One example is Helium: extremely low boiling point, gas, used in MRI machines and nuclear reactors, and becomes un-reusable.
Another is Phosphorus: important in DNA production, hard to obtain with 50% being lost in the process (100% initially obtained, but only 20% left at the end.), used a lot in fertilisers.
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What are periodic trends?
Periodic trends are all about the arrangement of the periodic table.
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What are the types of trends?
5 Main trends:
- Core charge
- Atomic Radius
- Electron negativity
- Reactivity
- First Ionisation energy
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What is the ‘Core charge’ and its formula?
Core charge = Is the measurement of attractive forces felt by the valence electrns towards the nucleus.
Formula: atomic number - e^- except valence e^-
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What is the atomic radius?
Atomic radius = measurement used for the size of atoms (distance between the nucleus and valence electrons.
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What increases the electronegativity?
The more strongly the valence electrons of an atom are attracted to the nucleus of the atom, the greater the electronegativity.
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The atomic radius _____ down a group, and _____ across a period.
The atomic radius INCREASES down a group, and DECREASES across a period.
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What is electronegativity and what is the most electromagnetic element?
It is the ability of an atom to attract electrons towards itself.
Fluorine is the most electronegative element.
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Electronegativity increases and decreases, when?
Electronegativity increases across a period from left to right.
Electronegativity decreases down a group.
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What is reactivity?
Reactivity is how easily an atom loses or gains electrons.
When electrons are lost it is mainly a metallic character. When electrons are gained it is mainly a non-metallic character.
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What is ionisation energy?
Ionisation energy refers to how much energy is needed to let go of the loosely held valence electron on the outermost shell.
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When does the ionisation energy increase and decrease?
The ionisation energy increases as you go across a period, and decreases when you go down a group.
*It decreases down a group because there are more energy shells.
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Why is it easier to remove a valence electron in Group 3 elements versus Group 2 elements?
This is because of the shielding effect (the valence electron in Group 3 is shielding the inner electrons)
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Why is it easier to remove a valence electron in Group 6 elements versus Group 5 elements?
This is because of the repulsion effect (the valence electrons in group 6 are repelling each other.)
