Bonding, Structure and Properties of Matter (pgs 112 - 121) Flashcards
How do metal atoms form ions?
They lose electrons to form positive ions
If an atom loses 3 electrons, what will be the charge on the ion formed?
3+
Explain why elements in the same group usually form ions with the same charge?
They have the same number of outer electrons, so have to lose or gain the same number of electrons to get a full outer shell
What charge do sulfur (group 6) ions have?
2-
Ionic bonding occurs between what types of element?
Metals and non-metals
How does an ionic bond form?
A metal atom loses electrons to form a positively charged ion. These electrons are gained by a non-metal atom, which forms a negatively charged ion. These oppositely charged ions are attracted to each other by electrostatic forces. (this is the ionic bond)
Describe the electron transfer that takes place when calcium (a group 2 metal) and chlorine (a group 7 non-metal) react to form calcium chloride (CaCl2)?
Each calcium atom loses its two outer electrons to form a Ca2+ ion. Two chlorine atoms gain ONE of these electrons each to form TWO Cl- ions
List two disadvantages of using dot and cross diagrams?
Any two from:
They don’t show the structure of the compound.
They don’t show the sizes of the ions
They don’t show how the ions are arranged in the compound
They make it look like the electrons shown by crosses are different from the electrons shown by dots
Give one advantage of using 3D models over Ball and Stick models to draw Giant Ionic Structures?
3D models allow you to show the sizes of the different ions compared to each other
Explain why Ionic compounds conduct electricity when dissolved in water?
The ions separate and can move freely in the solution, allowing them to carry an electric charge.
Define the term ‘covalent bond’?
shared pair of electtrons between two non-metal atoms
True or false. Atoms can share electrons in any of their shells. Explain your answer?
False.
Atoms can only share electrons in their outer shell
How many extra electrons does an atom gain for each single covalent bond it forms?
One extra shared electron
This diagram shows the structure of propane. What is the molecular formlar?
H H H l l l H - C - C - C - -H l l l H H H
C3H8
How many pairs of electrons are shared between the two oxygen atoms in an oxygen molecule?
Two Pairs
Give two physical properties of simple molecular substances?
Any two from:
they have very low melting/boiling points, they don’t conduct electricity
As simple molecules get bigger, what happens to the intermolecular forces between them?
They get stronger
In the displayed formular of a polymer, what does the ‘n’ represent?
H H l l ( - C - C - ) l l H H n
n is a large number showing that the unit is repeated a lot of times
Explain why most polymers are solid at room temperature?
Polymers are very large molecules and so the intermolecular forces between the molecules are strong. This means that a lot of energy is needed to separate the molecules
What type of bond is found between the two Nitrogen atoms in a nitrogen molecule?
a Triple covalent bond
Which has a higher melting point, polymers or giant covalent structures? Explain why?
Giant covalent structures. More energy is needed to break the covalent bonds between the atoms in giant covalent structures, than to break the intermolecular forces between polymer molecules.
Why can’t diamond conduct electricity?
It doesn’t have any free electrons or ions to carry a charge
Why is graphite soft and slippery?
Graphite contains layers of carbon atoms. There are no covalent bonds between these layers, so they are free to move over each other.
How is grapite simlar to metals?
Each carbon atom has one delocalised electron that is free to move throughout the structure. This means that graphite can conduct electricity and thermal energy (heat)
Give one practical use of nanotubes?
Any one from:
In electronic
To strengthen materials
What makes metals good conductors of electricity and heat?
The electrons in the outer shell of the metal atoms are delocalised and free to move around. These electrons can carry electric charge and thermal (heat) energy throughout the whole structure.
The layers of atoms in a metal can slide over each other. What property does this give metals?
Metals can be bent or formed into different shapes (they are malleable)
Which state of matter has a fixed volume but does not keep a fixed shape?
Liquid
How do the particles in a solid behave?
There are strong forces of attraction between particles. The particles are held close together in fixed positions to form a regular pattern with a fixed shape and volume.
Give one drawback of the particle theory model
Any one from:
Particles aren’t solid, inelastic spheres - they’re atoms, ions or molecules.
It doesn’t consider the forces between the particles, so you don’t know how strong they are
What state symbol would you use for a substance that is dissolved in water?
(aq)
Explain how the strength of the forces between particles can result in a substance having a low melting point?
The weaker the forces between particles, the less energy is needed to break them, and so the lower the melting point.
What state will a substance be in at a temperature below its melting point?
Solid
