Compounds, molecular bonds, and chemical reactions Flashcards
How many electrons are shared in a triple covalent bond?
Six
Where do hydrogen bonds occur?
Between molecules where covalently bonded hydrogen interacts with F, O, or N on another molecule
What occurs in a substitution reaction?
An atom or group of atoms from one reactant is substituted for an atom or group of atoms on a second reactant molecule
A charge attraction between positively charged metal ions and surrounding electrons is what type of bond?
Metallic
What type of bond forms between a metal and a non-metal ion?
Ionic
In a chemical equation, what is indicated by an arrow with a delta (Δ) above it?
Heated
What is the strongest of the dipole-dipole interactions?
Hydrogen bonds
Amino acids become proteins through what type of reaction?
Condensation reaction
Which are stronger, ionic or covalent bonds?
Ionic
Are dipole-dipole attractions intermolecuar or intramolecular forces?
Intermolecular forces
What is a metallic bond?
A charge attraction between positively charged metal ions and surrounding electrons
What is the purpose of VESPR (valence shell electron pair repulsion theory)?
It is a way to understand the three-dimensional nature of compounds
Do polar and non-polar compounds mix?
No, they are hydrophilic and hydrophobic respectively
An atom or group of atoms from one reactant being substituted for an atom or group of atoms on a second reactant molecule is what type of reaction?
Substitution reaction
What type of reaction is the opposite to an elimination reaction?
Addition
What occurs in an addition reaction?
Two or more reactants combine to form a single product
Which has a higher boiling point, ammonia or dihydrogen sulfide? Explain the reasoning
Are there H bonds to F, O, or N? If yes like ammonia, the bonds between molecules will be hydrogen bonds. If there are H but not F, O, or N like in dihydrogen sulfide, the bonds will be dipole-dipole attractions. Hydrogen bonds are the strongest of the dipole-dipole bonds, therefore ammonia would have the higher boiling point
What is indicated by three parallel lines in a Lewis dot structure?
Three pairs of shared electrons in a covalent bond
Do chemical equations occur in one direction?
Not necessarily, as shown by the arrows in equations the reaction can be one or two directional
Which are stronger, dipole-dipole attractions or dispersion forces?
Dipole-dipole attractions
In which type of reaction can the loss or gain of hydrogen or oxygen be considered?
Redox reaction
Why is sodium a soft metal?
It shares one valence electron
The geometry of a molecule is determined by electron ____
Repulsion
Unsaturated compounds can be produced from a saturated compound by what type of reaction?
Elimination reaction
What is written first when naming ionic compounds?
The name of the metal
Which type of reaction can change the shape of a single molecule?
Isomerisation reaction
Are non-polar compounds hydrophilic or hydrophobic?
Hydrophobic
In a chemical equation, what shows a substance to be in a liquid physical state?
‘𝘭’ in italics, normal font, and/or subscript
Describe the movement of electrons in metallic bonding
The nuclei are bound in a sea of surrounding electrons - vacant orbitals overlap and allow electrons to flow between neighbouring atoms
What type of bond is the sharing of electrons betweed two atoms?
Covalent
How is a covalent bond between three pairs of electrons shown in Lewis dot structures?
Three parallel lines
What is indicated by ‘R’ on a skeletal structure?
R is used to represent a side chain (there is no ‘R’ element)
In which type of bonding are valence electrons shared between cation nuclei?
Metallic
How many electrons are shared in a double covalent bond?
Four
Why does carbon ‘prefer’ to make 4 single covalent bonds than any combination of single, double, and triple?
It is easier to share one electron than it is to share two or three at once
What is the purpose of the arrows in chemical reactions?
To separate reactants an products, and to show direction of the reaction
What is the result of shared electrons in a covalent bond?
Compound stability
What occurs in metallic bonds?
The metal cation nuclei are bound in a sea of surrounding electrons
Is it easy to remove or add electrons if the ion has a full valence shell?
No - this is why noble gases have low reactivity
How many electrons are shared in a single covalent bond?
Two
A charge attraction between positive and negative ions is what type of bond?
Ionic
What are depicted in chemical equations?
Reactants, products, and the relative amount of both
Connections between atoms of a compound are called ____ bonds
Intramolecular
What does a plain line on a Lewis structure indicate?
The two atoms are planar (flat; on one plane)
In a chemical equation, what shows a substance to be in a gaseous physical state?
‘𝘨’ in italics, normal font, and/or subscript
What can be produced by chemical reactions?
New substances, colour changes, heat changes (not released or absorbed, 𝘤𝘩𝘢𝘯𝘨𝘦𝘥), solids to appear or disappear, gases to be formed, light or sound created
What is a redox reaction?
Oxidation-reduction reaction, wherein a reactant loses electrons (oxidises) and a reactant gains electrons (reduces)
Nucleotides become nucleic acids through what type of reaction?
Condensation reaction
Two reactants coming together to form two new products, one of which is eliminated, is what type of reaction?
Condensation reaction
Do hydrophilic and hydrophobic compounds mix?
No, they are polar and non-polar respectively
What type of atoms do ionic bonds form between?
A metal and a non-metal ion
What type of bond governs the physical properties of substances, intermolecular or intramolcular?
Intermolecular
Does one reactant give one product?
Not necessarily, one reactant can give multiple products
A high melting point means a high amount of energy is required to do what?
Break apart the bonds
What type of force is biochemically important for non-polar molecules?
Van der Waal’s forces
Give the stoichiometric ratio for the following equation.
C₃H₈ + 5O₂ → 4H₂O + 3CO₂
5 moles of O₂ are required to burn 1 mole of propane, which produces 4 moles of H₂O and 3 moles of CO₂
1 : 5 → 4 : 3
Can a dipole exist within a compound?
Yes, dipoles can exist within a compound
Gain of electrons results in what type of ion?
Anion
What is a dipole?
A molecule with regions that are opposite charges
Is melting governed by intermolecular or intramolecular bonds?
Intermolecular bonds
Reactants are written on which side of a chemical equation?
Reactants are written on the left
Main group elements react to achieve full outer shell valency of 8 electrons - what is this rule?
The octet rule
What is represented by a dot in Lewis dot structures?
An electron
Name three types of intermolecular bonds
Hydrogen bonds
Dipole-dipole bonds
Van der Waals forces
Briefly explain how Van der Waal’s forces (AKA dispersion/London dispersion forces) function
A larger proportion of electrons occurs on one side of an atom, creating a temporary dipole. Dispersion forces exist between the positive end of one temporary dipole and the negative end of another. This state is brief and very easily broken.
What does VESPR stand for?
Valence shell electron pair repulsion theory
Polymerisation of some monomers to form polymers is what type of reaction?
Condensation reaction
Are subscripts altered when balancing equations?
𝘕𝘰
Do multiple reactants give multiple products?
Not necessarily, multiple reactants can give one product
Which intermolecular forces are the strongest?
Hydrogen bonds
Most 3D structures of what type of bond have a crystal lattice structure?
Ionic
What is the term for a molecule with one +ve end and one -ve end?
A dipole; it is a dipolar molecule
Why is tungsten a hard metal?
It shares many valence electrons, creating more attactive forces between negative and positive
How is a covalent bond between two pairs of electrons shown in Lewis dot structures?
Two parallel lines
Hydrogen bonds are the strongest of which type of interactions?
Dipole-dipole
What does the mnemonic ‘oil rig’ stand for?
Oxidation is loss, reduction is gain
What are the different methods of representing biomolecules?
Skeletal/line structure
3D structure
Ball-and-stick model
Space-filling model
Dipole-dipole is what kind of interaction?
Polar electrostatic interaction
As ionic bonds are electrostatic attractions, what is required for a stable compound?
All charged to be balanced; positive and negative must be equal
What occurs in a condensation reaction?
Two reactants come together to form two new products, one of which is eliminated during the reaction
What is the term used to describe the physical state of something dissolved in water?
Aqueous
What does a dashed line on a Lewis structure indicate?
A dashed line indicates ‘inward’ direction, away from the reader
How do electron clouds enforce bonding angles?
By repelling each other
What is a dipole-dipole attraction?
The negative side of one dipole interacting with the positive side of another dipole
Most 3D ionic structures will have what kind of structure?
Crystal lattice
Two non-metals sharing valence electrons to complete their octets is what type of bond?
Covalent
What is the name of Al₂O₃ (aluminium and oxygen)?
Aluminium oxide
What is the name of KI (potassium and iodine)?
Potassium iodide
Are polar compounds hydrophilic or hydrophobic?
Hydrophilic
What is the name of symbols used to visualise atom valency?
Lewis dot structures
The loss of electrons is what process?
Oxidation
What are the steps for balancing equations?
- Write the atoms below each side of the equation (they should be the same)
- Write the number of atoms present next to its corresponding symbol (don’t forget the numbers out the front which are multipliers of the amount of molecules)
- Alter the coefficients to balance the equation (do 𝘯𝘰𝘵 alter the subscripts)
Is surface tension governed by intermolecular or intramolecular bonds?
Intermolecular bonds
Is boiling point governed by intermolecular or intramolecular bonds?
Intermolecular bonds
Name the classifications of organic chemical reactions
Addition Elimination Condensation Substitution Isomerisation Oxidation and reduction (redox) - subtype: combustion reaction
What type of bond forms between two non-metals?
Covalent
What separates multiple reactants or products in a chemical equation?
A plus (+) symbol
What are the reactants in a combustion reaction?
Carbon source + O₂
Name four physical properties of substances that are governed by intermolecular bonds
Boiling point, melting point, viscosity, surface tension
What is stoichiometry?
The measure of elements to determine the quantitative relationship between reactants and products in a reaction.
TLDR; knowing the amount of reactants or products tells us the amount of products or reactants respectively (due to the law of conservation of matter)
What occurs in oxidation?
A reactant loses electrons
In a chemical equation, what shows a substance to be in a solid physical state?
‘𝘴’ in italics, normal font, and/or subscript
What is written second when naming ionic compounds?
The name of the non-metal, usually the first syllable with the suffix ‘-ide’
The gain of electrons is what process?
Reduction
One mole of atoms is equal to how many atoms?
6.022x10²³
Which governs how different biomolecules are able to interact with each other, intermolecular or intramolecular forces?
Intermolecular forces
What is the weakest form of intermolecular force?
Van der Waal’s forces (AKA dispersion forces/London dispersion forces)
Which is stronger, covalent bonds holding a molecule together or dipole-dipole forces keeping the molecules together?
Covalent bonds
What type of reaction can produce unsaturated compounds from a saturated compound?
Elimination reactions
Loss of electrons results in what type of ion?
Cation
Two or more reactants combining to yield a single product is what type of reaction?
Addition reaction
What is an advantage of an ionic bonded substanes having a crystal lattice structure?
The crystal lattice structure is stronger/more solid/harder than the individual elements alone
The coefficients in a chemical equation tell us the ____ of the reaction
Stoichiometry
A bond formed by the sharing of electrons between two atoms is what type of bond?
Covalent
What occurs in an elimination reaction?
Reactant loses some atoms to form a compound with a new double bond, while those atoms form a new product/s
What is a covalent bond?
A bond formed by the sharing of electrons between two atoms
Which bond occurs between molecules where covalently bonded hydrogen interacts with F, O, or N on another molecule?
Hydrogen bonds
The force of intermolecular bonds is ____ in nature
Electrostatic
How many covalent bonds can carbon make?
Carbon has 4 valence electrons, so can make up to 4 covalent bonds
What are the three major types of intramolecular bonds?
Metallic, ionic, and covalent
Monosaccharides become polysaccharides through what type of reaction?
Condensation reaction
Why are hydrogen bonds the strongest of the dipole-dipole interactions?
They occur between the most electronegative atoms
What type of bond is an attration between cations and anions?
Ionic
Why do chemical reactions never cause a loss or gain in matter?
The Law of Conservation of Matter - in any given system that is closed to the transfer of matter (in and out), the amount of matter in the system stays constant.
Which are stronger, intramolecular or intermolecular bonds?
Intramolecular
What does a solid/thick/bold line on a Lewis structure indicate?
A thick/bold line indicates ‘outward’ direction, towards the reader
What is an aqueous substance?
Something dissolved in water
What is an ionic bond?
A charge attraction between positive and negative ions
Which governs states of matter, intermolecular or intramolecular forces?
Intermolecular forces
In a chemical equation, what shows a substance to be in a aqueous physical state?
‘𝘢𝘲’ in italics, normal font, and/or subscript
How are physical states shown in chemical equations?
𝘴 (solid), 𝘭 (liquid), 𝘨 (gas), 𝘢𝘲 (aqueous)
A dipole that spans the whole molecule results in that molecule being referred to as a ____ molecule
Polar
What occurs in an isomerisation reaction?
A single molecule undergoes electron reorganisation; this is intermolecular rearrangement where transposition of double bonds or cis-trans rearrangement of double bonds occurs
Is viscosity governed by intermolecular or intramolecular bonds?
Intermolecular bonds
What is almost always required for an addition reaction?
One reactant to have a multi-covalent bond
The overall polarity of molecules is due to what?
Electron density
Direct reaction of many compounds with O₂ is accompanied with what type of reaction?
Combustion reaction
What is the octet rule?
Main group elements react to achieve full outer shell valency of 8 electrons; gain or loss of electrons occurs to ensure a valency of 8
A bond between two carbon atoms is what type of bond?
Covalent
How is a covalent bond between one pair of electrons shown in Lewis dot structures?
A single line
Van der Waal’s forces are biochemically important for what substances?
Non-polar molecules
The more energy that is required to break apart the bonds in a substance, the higher the ____ ____ (physical property) will be
Melting point
What is never caused be chemical reactions?
Loss or gain in matter
If dipoles can exist within a compound, what is true about multiple dipoles in a compound?
The dipoles within compounds can cancel each other out
What metabolic process involves a set of reactions which includes electron carriers facilitating generation of ATP?
Complete oxidation of glucose
What occurs in reduction?
A reactant gains electrons
A reactant losing some atoms to for a compound with a few double bond while those atoms form a new compound/s is what type of reaction?
Elimination reaction
The negative side of one dipole interacting with the positive side of another dipole forms what kind of attraction?
Dipole-dipole
Products are written on which side of a chemical equation?
Products are written on the right
What molecular mass unit is used in biochemistry?
Da (Daltons)
Give an example of a molecule in which multiple dipoles cancel each other out, resulting in an overall non-polar molecule
Carbon dioxide
What type of reaction can be initiated by heat or light and is actioned by enzymes?
Isomerisation reaction
Electrostatic forces that keep matter together are what type of bond, intermolecular or intramolecular?
Intermolecular bonds
What type of reaction is the opposite to an addition reaction?
Elimination
What happens to electrons in metallic bonding?
The valence electrons are shared between cation nucei via overlapping orbitals
What are the products in a combustion reaction?
CO₂ + H₂O + energy
If a stick leads to an empty space in a skeletal structure, what is actually at the end?
A hydrogen atom
What is indicated by two parallel lines in a Lewis dot structure?
Two pairs of shared electrons in a covalent bond
