structure and bonding-c3 Flashcards
three states of matter(read bc idk how to make question)
Materials come in different forms-solid, liquid and gas. These are the three states of matter. Which state something is at a certain temperature depends on how strong the forces of attraction are between the particles of the material. How strong the forces are depends on three things:
- the material
- the temperature
- the pressure
What does particle theory show?
You can use a model called particle theory to explain how the particles in a material behave in each of the three states of matter by considering each particle as a small, solid, inelastic shape.
Facts about solids?
-In solids, there are strong forces of attraction between particles, which holds them close together in fixed positions to form a very regular lattice arrangement.
The particles don’t move from their positions, so all solids keep a definite shape and volume and don’t flow like liquids.
-The particles vibrate about their positions- the hotter the solid becomes, the more they vibrate(causing solids to expand slightly when heated.
Facts about liquids?
- In liquids there is a weak force of attraction between the particles. They’re randomly arranged and free to move past each other, but they tend to stick closely together.
- Liquids have a definite volume but don’t keep a definite shape, and will flow to fill the bottom of the container.
- The particles are constantly moving with random motion. The hotter the liquid gets, the faster they move. This causes liquids to expand slightly when heated.
Facts about gases?
In gases, the force of attraction between the particles is very weak-they’re free to move and are far apart. The particles in gases travel in straight lines.
- Gases don’t keep a definite shape or volume and will always fill any container.
- The particles move constantly with random motion. The hotter the gas gets, the faster they move. Gases either expand when heated or their pressure increases.
What are the limitations of the particle theory?
Particle theory is a great model for explaining the three states of matter, but it isn’t perfect. In reality, the particles aren’t solid or inelastic and they aren’t spheres- they’re atoms, ions or molecules. Also, the model doesn’t show the forces between the particles, so there’s no way of knowing how strong they are.
Explain the process of melting?
When a solid is heated, it’s particles gain more energy. This makes the particles vibrate more, which weakens the forces that hold the solid together. At a certain temperature, called the melting point, the particles have enough energy to break free from their positions. This is called melting and the solid turns into a liquid.
Explain the process of boiling?
When a liquid is heated, the particles gain a lot of energy. This makes the particles move faster which weakens breaks the bonds holding the liquid together. At a certain called the boiling point, the particles have enough energy to break their bonds. This is boiling(or evaporating). The liquid becomes a gas.
Explain the process of condensing?
As a gas cools, the particles no longer have enough energy to overcome the forces of attraction between them. Bonds form between the particles. At the boiling point, so many bonds have been formed between the gas molecules that the gas becomes a liquid. This is called condensing.
Explain the process of freezing?
When a liquid cools, the particles have less energy, so move around less. There is not enough energy to overcome the attraction between the particles, so more bonds form between them. At the melting point, so many bonds have formed between the particles that they are held in place. The liquid becomes a solid. This is freezing.
What does the amount of energy needed for a substance to change state depend on?
The amount of energy needed for a substance to change state depends on how strong the forces between the particles are. The stronger the forces, the more energy is needed to break them, and so the higher the melting and boiling points of the substance.
How to predict the state of a substance in a exam?
If the temperature is below the melting point of the substance, it will be a solid. If it is above the boiling point, it will be a gas. If it’s in between the two points, then it’s a liquid.
What are ions?
Ions are charged particles
How do ions form?
When atoms lose or gain electrons to form ions, all they are doing is trying to get a full outer shell like a noble gas. Atoms with full outer shells are very stable.
Do metals form positive ions?
Yes, when metals form ions, they lose electrons from their outer shell to form positive ions.
Do non metals form negative ions?
Yes, when non metals form ions, they gain electrons into their outer shell to form negative ions.
If 2 electrons are lost, what is the charge of the ion?
If 3 electrons are gained what is the charge of the ion?
2+
3-
Explain ionic bonding?
When a metal and non metal react together, the metal atom loses electrons to form a positively charged ion and the non metal gains these electrons to form a negatively charged ion.
These oppositely charged ions are strongly attracted to one another by electrostatic forces. This attraction is called an ionic bond.
What groups are most likely to form ions?
Groups 1,2,6 and 7
What ions do group 1 and 2 form?
Group 1 and 2 are metals and they form positive ions bc they lose electrons
What ions do group 6 and 7 form?
Group 6 and 7 are non metals, they form negative ions bc they gain electrons
What are dot and cross diagrams?
They show the arrangement of electrons in an atom or ion. Dot and cross diagrams are useful for showing how ionic compounds are formed, but they don’t show the structure of the compound, the size of the ions or how they are arranged.
What is an ionic compound?
An ionic compound is any compound that only contains ionic bonds.
What structure do ionic compounds have?
Ionic compounds have a structure called a giant ionic lattice. The ions form a closely packed regular lattice arrangement and there are very strong electrostatic forces of attraction between oppositely charged ions, in all directions in the lattice.
What are the advs and disadvs of a 3d model?
The model shows the relative sizes of the ions, as well as the regular pattern of an ionic crystal, but it only lets you see the outer layer of the compound.
What are the advs and disadvs of a ball and stick model?
It shows the regular pattern of an ionic crystal and shows how all the ions are arranged. It also suggests the crystal extends beyond what is shown in the diagram. The model isn’t to scale, so the relative sizes of the atom may not be shown. Also, in reality, there are no gaps between the ions.
Why do ionic compounds have high melting and boiling points?
They all have high melting points and high boiling points due to many strong bonds between the ions. It takes lots of energy to overcome this attraction.
What are some properties of ionic compounds?
When they are solid, the ions are held in place, so the compounds can’t conduct electricity. When ionic compounds melt, the ions are free to move and they will carry electric current.
Some ionic compounds also dissolve easily in water. The ions separate and are all free to move in the solution, so they’ll carry electric current.
What is covalent bonding?
This is where atoms share electrons with each other so that they have got full outer shells.
Explain covalent bonding?
When non metal atoms bond together, they share pairs of electrons to make covalent bonds. The positively charged nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces, making covalent bonds very strong.
