Bonding Flashcards
What are the three different types of bonding
Ionic bonding, metallic bonding and covalent bonding
What are the characteristics of covalent bonds
- They mainly take place between of non-metals
- they form molecules
- atoms have a noble gas structure
- molecules are held together by the shared electron pair
What are the characteristics of an ionic bond
-Metals transfer electrons to non metal
-positive and negative ions attract each other by electrostatic forces because they are oppositely charged
-the electrostatic Attraction is the ionic bond
-ionic bonds DO NOT form molecules
- they form a crystal lattice that is built up of alternate positive and negative ions
What are the characteristics of metallic bonding
- the atoms of the metal have 1-3 valence electrons
- ionisation energy of a metal is low thus little energy is needed to delocalise
-atoms in a metal are tightly packed together in an orderly crystal lattice
Explain why metals glow by referring to metallic bonds
The sea of delocalised electrons can reflect light and therefore cause the surface to shine
Explain why metals glow by referring to metallic bonds
The sea of delocalised electrons can reflect light and therefore cause the surface to shine
Explain why metals are good conductors of electricity by referring to metallic bonds
The sea of delocalised electrons can move freely and act as charge carriers in the solid and liquid phase
Explain why metals are good conductors of heat by referring to metallic bonds
The sea of delocalised electrons act as carriers of heat
Explain how metals are shapeable by referring to metallic bonds
The atoms, although they are firmly bound together, can slide over one another, which allows metal to bend and stretch
Explain How metals have a high density by referring to metallic bonds
The atoms of metals in the solid phase are packed closely together In a metal lattice
How is steel formed
With iron and carbon
How is stainless steel formed
Iron, chromium, nickel
How is bronze formed
Copper and tin
What are molecular shapes
The special three dimensional arrangement of atoms in a molecule
What properties does the shape of a molecule influence
Boiling point, melting point, density and the type of chemical reactions it will undergo
How do we predict the geometric shape of molecules formed through non-metal atoms
Valence Shell electron pair repulsion model (VSEPR model)
What idea is the VSEPR model based on
The idea that structural electron pairs repel each other as far as possible in space. This ensures the lowest possible potential energy, which as a result makes it more stable. The positions they take up determine the angles between the bonded atoms in a molecule
What are the two types of geometry the VSEPR model works with
Electron pair geometry and molecular geometry
What are the five ideal molecular shapes
Linear, trigonal planar, tetrahedral, trigonal bipyramidal, octahedral
What is the bond angle for a linear molecule
180 degrees
What is the bond angle for a trigonal planar molecule
120 degrees
What is the bond angle in a tetrahedral molecule
109,5 degrees
What is the bond angle in a trigonal bipyramidal molecule
120 degrees and 90 degrees
What is the bond angle in an octahedral molecule
90 degrees
Explain the formation of non ideal molecules
- lone pairs are slightly bigger and repel each other and other bond electrons more, so the bonding angle closes slightly.
- there are three type of repulsion forces (LP-LP, LP-BP, BP-BP) whose repulsion is in order of biggest to smallest
- however if the number of atoms is equal to the number of electron pairs it will keep the ideal molecular shape.
What are the two types of non-ideal shapes
Angular and trigonal pyramidal
What is the bond angle for trigonal pyramidal molecules
107 degrees
What is the bond angle for angular molecules
104,5 degrees
How do you format summary answer of bond angles
- talk about number electron pairs (a double bond is treated as a single bond with one bonding pair)
- talk about electron pair geometry shape
- talk about number of atoms around central atom
- talk about molecular geometry shape
- talk about bond angle (refer to specific angle eg. N-H-N is 107 degrees) and if there is lone pairs talk about how angle is now slightly smaller than ideal shape.
What does electronegativity depend on
Electron structure: the tendency to release or obtain electrons to form the octet structure. Non metals have higher electronegativity than this of metals
Atomic radius: the closer the valence electrons are to the nucleus the tighter it holds on to it
Energy levels: the more energy levels there are the more electrons there are shielding the nucleus from holding on more tightly to the valence electrons
What is bond length
The average distance between the nuclei of two atoms in a molecule
What Influences the bond length of bonded atoms
Atom size, electronegativity, and bond order
How does the size of the atom influence the bond length
The bond length increases as the size of the atom increases. Thus weakening the bond strength
How does electronegativity influence bond length
The greater the difference in electronegativity will lead to a shorter bond length and thus a stronger bond
What is bond order
Bond order is the number of bonds (single, double, triple) which exists between two atoms
How does bond order influence bond length
The higher the bond order the shorter the bond length and the stronger the bond
What is bond energy
The energy necessary to break one mol of a specific covalent bond in the gaseous phase
What does positive (+) energy represent
Energy is absorbed
What does negative (-) energy represent
Energy is released
What is the relationship between bond length and bond energy
Inverse relationship. The stronger the bond the shorter the bond length and the weaker the bond the longer the bond length
What are the factors that influence bond energy
Bond length
Bond energy
Size of the atom
Bond order
