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Flashcards in Chemistry Deck (110)
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1

What are compounds

Substances in which atoms of two or more elements are chemically combined

2

What does chemical bonding involve

Either transferring or sharing electrons in the highest occupied energy levels (shells) of atoms in order to achieve the electronic structure of a noble gas

3

When are ions formed

When atoms form chemical bonds by transferring electrons

4

What are positively charged ions

Atoms that lost electrons

5

What are negatively charged ions

Atoms that gained electrons

6

What are alkali metals

The elements in Group 1

7

What do alkali metals all react with non metal elements to form

Ionic compounds in which the metal ion has single positive charge

8

What are halogens

The elements in Group 7

9

What do halogens all react with alkali metals to form

Ionic compounds in which the halide ions have a single negative charge

10

What is an ionic compound

A giant structure of ions

11

What are ionic compounds held together by

Strong electrostatic forces of attraction between oppositely charged ions that act in all directions of the lattice

12

When are covalent bonds formed

When atoms share pairs of electrons. These bonds between atoms are strong

13

What are examples of simple molecules that some covalently bonded substances consist of

H2, Cl2, O2, HCl, H2O, NH3, CH4

14

What are examples of macromolecules

Diamond and silicon dioxide

15

What are macromolecules

Substances that have giant covalent structures

16

What do metals consist of

Giant structures of atoms arranged in a regular pattern

17

What can the electrons in the highest occupied energy levels do as a result of being delocalised

Be free to move through the whole structure. This corresponds to a structure of positive ions with electrons between the ions holding them together by strong electrostatic attractions

18

What substances have relatively low melting and boiling points

Substances that consist of simple molecules

19

How strong are the intermolecular forces of simple molecules

Weak. It is these intermolecular forces that are overcome, not the covalent bonds, when the substance melts or boils

20

Why don't substances that consist of simple molecules conduct electricity

Because the molecules do not have an overall electric charge

21

What are giant ionic lattices

Ionic compounds that have regular structures

22

Why do giant ionic lattices have high melting and boiling points

Because of the large amounts of energy needed to break the many strong bonds

23

What do ionic compounds do when melted or dissolved in water

Conduct electricity because the ions are free to move and carry the current

24

How are macromolecules formed

By atoms that share electrons

25

Why is diamond very hard

Because each carbon atom in diamond forms four covalent bonds with other carbon atoms in a giant covalent

26

Why is graphite soft and slippery

Because in graphite, each carbon atom bonds to three others, forming layers. The layers are free to slide over each other because there are no covalent bonds between them

27

Why is graphite able to conduct heat and electricity

Because in graphite one electron from each carbon atom is delocalised. It is these delocalised that allow graphite to conduct heat and electricity

28

Why is graphite similar to metals

It has delocalised electrons

29

What is the structure of fullerenes based on

Hexagonal rings of carbon atoms

30

What can fullerenes be used for

Drug delivery into the body
In lubricants
As catalysts
In nanotubes for reinforcing materials e.g. in tennis rackets