CHEMISTRY FLASHCARDS

FROM SYLLABUS AND BOOK

Does the energy increase or decrease as the electrons get further from nucleus?

• energy increases

What are the 7 diatomic molecules?

1. H_² (Hydrogen)

2. N₂ (Nitrogen)

3. O₂ (Oxygen)

4. F₂ (Fluorine)

5. Cl₂ (Chlorine)

6. Br₂ (Bromine)

7. I₂ (Iodine)

Do all electrons in a atom have the same energy? Why?

• They have different energies as the further from nucleus the more energy

What are Isotopes?

• Atoms with same number of protons

• different neutrons

What does the symbol A indicate? How do you calculate it?

• Atomic number

• Protons + neutrons

What are the three subatomic particles?

• protons

• neutrons

• electrons

What does the symbol Z indicate?

• The number of protons

Whats the difference between negative ions and positive ions?

• Negative - More electrons than protons (- = gain) - compared to neutral atoms

• Positive - Less electrons than protons (+ = lost) - compared to neutral atoms

Whats the difference between a period number and group number on the periodic table?

• period - row (number of energy levels (shells))

• group - column group - number of valence electrons

how many electrons does the 1st, 2nd and 3rd shell contain? What model is this called?

• 1st = 2

• 2nd = 8

• 3rd = 18

• Bohr’s Atomic Model

fill in the table:

Shell	Subshell	Maximum electrons	Maximum subshell	Maximum orbital

Shell	Subshell	Maximum electrons	Maximum subshell	Maximum orbital
1	1s	2	2	1
2	2s, 2p	8	6	3
3	3s, 3p, 3d	18	10	5
4	4s, 4p, 4d, 4f	32	14	7

What is the electron configuration order and its energy order - sub-shells number of orbitals and electrons?

Which shells has the highest and lowest energy?

• s (1 orbital, max 2 electrons) - lowest energy

• p (3 orbitals , max 6 electrons)

• d (5 orbitals , max 10 electrons)

• f (7 orbitals , max 14 electrons) - highest energy

Why does the orbital energy increase?

• decrease in effective nuclear attraction - reduces the nucleus’s control to hold the electron

• shielding and distance increases - increases energy

What are the 3 principals? provide an example for each

1. Aufbau principal - electrons must fill lower atomic and energy orbitals before occupying the higher ones. (front of lecture theatre to back of theatre)

2. Pauli exclusion principal - hold max of 2 electrons with opposite spins. Seesaw two people sit but one goes spins/goes up and the other spins opposite/ goes down.

3. Hund’s rule - electrons occupy first orbital at a time before pairing. everyone gets own work, before pairing up

What is ionisation energy?

• energy required to remove one valence electron

Why does ionisation energy increase across the same shell (period)?

• across period - nuclear charge increases causing the electrons to be more attracted to the nucleus making it harder to remove. Whilst, the shielding remains relatively similar.

Why is there a larger jump after valence electrons are removed?

• Next electron is in the inner shell and is closer and more attracted to the nucleus

How does successive ionisation energy indicate valence electrons? for example, what does it indicate when its after the 3rd electron?

• Number of small increases before a dramatic increase = number of valence electrons

• That the atom has 3 valence electrons

Why do Isotopes of same element behave chemically similar? But not physically?

Chemically:

• Same number of electrons and similar bonding and electron configuration

Physically:

• due to different neutron numbers it changes its physical properties, such as density and mass

What does “X” stand for in Isotopes? (^{A_Z X)}

• X = Element symbol

What does “A” stand for in Isotopes?

• Mass number

Why is the weighted average often recorded for an isotope?

• Takes into account of weight and abundance of each isotope

What does abundance mean? provide an example

• Is the amount of something that exists compared to the rest.

• For example C-35 (75%) and C-37 (25%). C-35 is more abundant as it appears more often in nature.

Why is RAM not a whole number? Why do some elements have fractional RAM values?

• Weighted average of different isotopes contain different mass and abundance

• Many elements exist as a mixture of different Isotopes - so average is not whole.

Group metals and gases Table - Perodic trends and tables. Fill in the table below

Group:	Name:	Properties:	Valence electrons
		-
		-
		-
		-

 

Group:	Name:	Properties:	Valence electrons
1	Alkali	-              Soft metals -              Most reactive -              Reacts with water	From group 1 to 18, it decreases in reactivity
2	Alkali earth metals	-              Hard metals -              Higher temperature to react with water -              Reacts slower
17	Halogens	-              Non-metallic -              Diatomic molecules -              Reacts highly with 1 and 2 metals -              decrease in reactivity from F -> A
18	Nobel gases	-              Least/no reactive

 

What is the shielding effect?

• Inner electrons block the nucleus’s ability to pull on the outer electrons

What is electronegativity? and does an increases/ decrease in energy indicate a high/low attraction? answer for both an increase and decrease in energy

• Ability of atom to attract shared electrons while being bonded to another atom

• increase in energy = high attraction

• decrease in energy = low attraction

What are Transitional elements?

• Elements that form ions due to various oxidation states (loss or gain of electrons)

• found in d-block

• forms one or more ions - as it loses different numbers of valence electrons

Properties of Metal and non-metal include? Also why metals conduct electricity

Metal:

• Good conductors of heat and electricity - contains delocalised electrons which move around and carry charge.

• Ductile (shaped without breakage)

• Malleable

• Lustrous (Shiny)

Non-Metals:

• Poor conductors of heat and electricity - no delocalised or free electrons - doesn’t carry charge

• dull (not shiny)

• brittle - breakable

What are the properties for metallic? Types of bonding (1/4)

• high melting and boiling points

• strong bond between delocalised electrons and metal ions

• conducts electricity in liquid and solid

What are the properties for ionic? Types of bonding (2/4)

• No conduction of electricity in solids but does in liquids

• Ions are fixed in solid but free in liquid

• high melting and boiling points

• strong electrostatic attraction between opposite charged ions

What are the properties for covalent molecular? Types of bonding (3/4)

• low melting and boiling point

• weak intermolecular force

• doesn’t conduct electricity in liquid or solids

• no free or delocalised ions

What are the properties for Giant Covalent network? Types of bonding (4/4)

• extremely high melting and boiling point

• does not conduct electricity

• no charged particles

What are Ions?

Ions are a group of atoms that have lost or gained electrons

• loses electron - positive ion

• gains electron - negative ion

What is electrostatic attraction?

• Type of force that pulls and holds oppositely charged particles together

What are the oxide changes and why across period 3? Why?excluding the noble gas

• Basic → Basic (if it produces OH^-) → Amphoteric→ Rest is Acid (if it produces H⁺)

• this is due to metals (Basic) easily losing electrons and forming Ionic compounds and O².

• whereas, non-metals (acidic) share electrons and dont release O² forming covalent compounds.

What are compounds?

• products formed in a reaction

What particle attraction does Ionic bonding attract?

• oppositely charged particles

What is covalent bonding?

• sharing of electrons

What does valency mean? and what does the number of valency indicate?

• Number of bonds an atom can form

• number of valency = number of covalent bonds

molecular prefixes

Number of atoms:	Prefix-	Number of atoms:	Prefix-
1		6
2		7
3		8
4		9
5		10

Number of atoms:	Prefix-	Number of atoms:	Prefix-
1	Mono-	6	Hexa-
2	di-	7	Hepta-
3	Tri-	8	Octa-
4	Tetra-	9	Nona-
5	Penta-	10	Deca-

What is are the types of formulas? (Empirical and molecular?)

• Empirical formula - simplified whole number ratio of atoms in a compound

• molecular formula - shows the actual number of each atom in a molecule

Whats the difference between a lone and a bonding pair (lewis dot structure)?

• lone pair = no sharing of electrons (dots (..))

• Bonding pairs = sharing of electrons (lines (-))

What is a pure substance and what are two types?

• Elements and compounds

• pure substance is one type of particle

What’s the difference between Homogeneous and Heterogeneous mixtures?

• Homogeneous mixture - particles evenly mixed and throughout visibly same (HOME)

• Heterogeneous mixture - particles are unevenly mixed and parts are visibly different (HIT and mix)

What does Lattice mean?

• Fixed 3D repeated pattern of a particle in a solid.

What is an Allotrope? and What is a phase change? provide an example of each.

• Allotrope - same element and physical state but different structural form - carbon: diamond and graphite

• Phase change - same substance changes in different physical state (solid, liquid and gas)

What is the difference between exothermic and endothermic reactions? provide an example for each. Also what is each of its product energy levels.

Exothermic reaction:

• Is the exist of heat from the system into its surroundings. E.g. Campfire.

• Causes the net energy to be released so the products heat is lower than reactants

• Negative heat and feels warm

Endothermic reaction:

• Is the absorption of heat from the surroundings into the system. E.g. heat packs

• Energy is absorbed so products heat is higher than reactants

• Positive heat and feels cold

What happens to the energy when bonds break and bonds form?

• Bonds break - absorption of energy

• Bond forming - release of energy

What does activation energy and (triangle/delta symbol) H indicate?

• Activation energy is the minimum amount of energy required to start/produce a reaction or breakage of bonds

• (triangle/delta symbol) H indicates the enthalpy change (energy change) during a reaction.

What is a bond enthalpy? And why is it measured in averages?

• activation energy to break one mole of a bond in a gas state

• Average values are taken from different molecules

What is a mole? Refer to Avogadro’s number. Also why is moles useful

• fixed substance containing 6.02 × 10²³ particles

• Count particles by measuring its mass

What are the four molecular shapes? What are its characteristics: degree, bonding electrons, lone pairs?

• Linear: 180°, 2 bondings and 0 lone

• Bent: 104.5°, 2 bonding and 1 lone

• Trigonal Planar: 120°C, 3 bonding and 0 lone

• Trigonal Pyramidal: 107°, 3 bonding and 1 lone

• Tetrahedral: 109.5°C, 4 bonding and 0 lone

What does an increase and decrease in lone pairs result in?

• Increase = smaller bond angles