chemistry - ions Flashcards
What is independent variable?
The variable for which values are changed.
What does the limitation of the simple particle model include?
In the model there are no forces so all particles are shown as spheres and the spheres are solid.
What is the dependent variable?
The variable for which the value is measured.
What are control variable?
The ones which must be kept the same (constant).
What are the three states of matter?
Solid, Liquid and Gas.
The stronger the forces between the particles…
…the higher the melting and boiling point of the substance.
What are the three states of matter shown as in chemical equations?
(s) (l) (g) with (aq) for aqueous solutions.
Why do metal atoms lose electrons?
To become positively charged ions.
Why do non-metal atoms gain electrons?
To become negatively charged ions.
What is an ionic compound?
A giant structure of ions.
How are ionic compounds held together?
By strong electrostatic forces of attraction between oppositely charges ions.
What happens when atoms share pairs of electrons?
They form covalent bonds. These bonds between atoms are strong.
What have very large molecules?
Some covalently bonded substances such as polymers.
What have giant covalent structures?
Some covalently bonded substances such as chemical and silicon dioxide.
What represents a single bond?
A single line.
What do metals consist of?
Giant structure of atoms arranged in a regular pattern.
What are the electrons in the outer shell of metal atoms?
Delocalised so they are free to move through the whole structure. The sharing of delocalised electrons gives rise to strong metallic bonds.
What is the melting and boiling point of ionic compounds? And Why?
High because of the large amounts of energy needed to break the many strong bonds.
What happens when ionic compounds are melted or dissolved in water?
They conduct electricity because the ions delocalised and so charge can flow.
What substance consist of small molecules?
Usually gases or liquids that have relatively low melting and boiling points.
What happens with the intermolecular forces between small molecules?
They increase with the size of the molecules so larger molecules have higher melting and boiling points.
How are the atoms in the polymer molecules linked?
To other atoms by strong covalent bonds.
How strong are the intermolecular forces between polymer molecules?
Relatively strong so these substances are solids at room temperature.
What substances consists of giant covalent structures?
Solids with very high melting points which its atoms are all linked by strong covalent bonds.
What are examples of giant covalent structures?
Diamond and Graphite (forms of carbon) and silicon dioxide (silica).
What is a metal’s melting and boiling point? And why?
High because they have giant structures of atoms with strong metallic bonding.
How are atoms arranged in pure metals?
Layers which allow metals to be bent and shaped.
Why are metals good conductors of electricity?
The delocalised electrons in metal carry electrical charge through the metal.
When in graphite, each carbon atom forms three covalent bonds with three other carbon, what does this form?
Layers of hexagonal rings which have no covalent bonds between them.
What is graphene?
A single layer of graphite and has properties that make it useful in electronics and composites.
What are fullerenes?
Molecules of carbon with hollow shapes.
What is the structure of fullerenes?
Hexagonal rings of carbon atoms which may contain rings with five or seven carbon atoms.
What are carbon nanotubes?
Cylindrical fullerenes.
What are carbon nanotubes’ properties?
High length to diameter ratios. Useful for nanotechnology, electronics and materials.
What’s are precise measurements.
Ones where there is little spread about the mean value.
What’s are accurate measurements?
Close to the true value.
What do valid experiments answer?
The question being asked.
When is measurement repeatable?
If the experiment is carried out by the same person using the same method and has the same results.
What does reproducible mean?
When the same experiment is carried out by a different person or group and you get the same results.
