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Description
Flashcards by grace.hanc, updated more than 1 year ago
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Created by grace.hanc
over 8 years ago
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| Question | Answer |
| When are ions formed? | When an atom loses or gains one or more electrons |
| What happens to a positive ions? | Lose electrons to from positive ions |
| What happens to negative ions? | Gain electrons to form negative ions |
| Number or charges on a positive ion | Is the same as the group number of the element |
| Number of charges on negative ion | Is (8 - group number of element) |
| What is a noble gas structure like? | Stable electronic structure Have 8 electrons on outer shell No tendency to lose or gain electrons Example: neon and argon atoms |
| What is an ionic compound? | It contains positive and negative ions, formed when atoms transfer electrons |
| Features of group 1 elements | Metals React with non metals to form ionic compounds Produce ions with 1+ charge |
| Features of group 7 elements | Non metals React with metal elements to form ionic compounds Produce ions with 1- charge |
| Ionic bonds | An ionic compound is a GAINT STRUCTURE of ions. They are help in a regular arrangement called a lattice. Are strong electrostatic forces of attraction between oppositely charged ions |
| Metal atoms.... | lose one or more electrons number of charge = same as group number |
| Non-metal atoms... | Gain one or more electrons (8 - group number) |
| What is a covalent bond? Where are they formed? | Form when atoms share electrons. It is a shared pair of electrons. It forms between two non-metal atoms. |
| What is a simple molecule + example? | It contains only a few atoms joined together by covalent bonds Hydrogen |
| Properties of simple molecules | Low melting point Low boiling point Tend to be gases or liquids at room temperture |
| What is intermolecular forces and where are they found? | Week attractive forces between simple molecules When melted or boiled: Intermolecular forces are easy to overcome or break but the covalent bonds do not break |
| What is a macromolecules and a example of what they can be? | They have giant covalent structure/ Each molecule contains very many atoms joined together by covalent bonds They can be elements (diamond) or compounds (silica) |
| What properties must a substance have to conduct electricity? | + must have electrically charged particles particles must be free to move |
| Do substances with simple molecules conduct electricity? | substances that consist of simple molecules cannot conduct electricity because the molecules do not have an overall electrical charge |
| What are some properties of a diamond? | Each atom is bonded to four others Strong covalent bonds between atoms Does not have delocalised electrons High melting point Solids at room temperature Giant covalent lattice |
| What is an ionic bond? | Is an electrostatic force of attraction between oppositely charged ions High melting point High boiling point |
| Ion properties | Ions are charged but they cannot carry an electric current Are free to move |
| Why can metals conduct heat and electricity? | Because they have delocalised electrons which are free to move through their structure which can conduct heat and electricity |
| Why can metals be shaped easily? | Because they have layers of atoms which can slide over each other. |
| What is an alloy? | Is a metal mixed with one or more other elements which is usually other metals |
| What is shape memory alloys? | Can be returned to their original shape after being stretched or bend |
| What is a polymer? | Are very large molecules made when small molecules join together |
| What does thermosoftening polymers consist of? | Individual tangled polymer chains |
| What happens to thermosoftening polymers when heated? | Soften and melted Intermolecular forces are weakened which lets the chains slide over each other easily |
| What does LDPE stand for? | Low density poly(ethene) Flexible Holds colder tempertures |
| What does HDPE stand for? | High density poly(ethene) Stronger Less flexible Holds higher tempertures |
| What size does nanoscience concern? | 1nm and 100nm in size |
| 1nm is how many millimetres? | one millionth |
| Properties of nanoscience | high surface area to volume ratio |
| Why can nanoparticles be used a catalysts? | Because they have a large surface area |
| Uses of nanoparticles? | Computers Catalysts Coatings High selective sensors detect substances like polluting gases Lighter ans stronger construction materials Sunscreens Deodorants |
| Properties of nanotubes | Very strong Conduct electricity |
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