Atoms, elements and compounds Flashcards
What is the relative charge of a proton?
+1
What is the relative charge of a neutron?
no charge
What is the relative charge of an electron?
-1
What is the relative mass of a proton?
1
What is the relative mass of a neutron?
1
What is the relative mass of an electron?
0.00054 (1/2000)
What is a proton number?
number of protons in the nucleus of an atom
What is a nucleon (mass) number?
total number of protons and neutrons in the nucleus of an atom
What are isotopes?
atoms of the same element which have the same proton number but a different nucleon number
Why do isotopes have the same properties?
they have the same number of electrons in their outer shell
What are the two types of isotopes?
radioactive
non radioactive
What is a medical use of radioisotopes?
Sterilizing equipment
Cancer treatment
What is an industrial use of radioisotopes?
Checking for oil leaks in pipelines
What is an element?
A substance made of one type of atom
What is a mixture?
substance contains two or more elements or compounds that are not chemically bonded together
What is a compound?
substance made up of two or more different types of atoms joined together by chemical bonds
What is an alloy?
a mixture of a metal with other elements
How are ions formed?
Electron loss/gain
What is an ionic bond?
Attraction between positive ions and negative ions
What is an ion?
Electrically charged particle
What is an ionic bond between?
Metals + non-metals
How are ionic bonds formed?
Ions transfer electrons from one atom to another
An ionic lattice has + & - ions and is held together by
strong electrostatic bonds
What are 4 properties of ionic compounds?
High fixed points
Poor conductors as solid
Hard
Soluble in water
Why do ionic compounds have high fixed points?
(ionic bonds strong)
◆ Lots of energy required to overcome electrostatic attraction
Why are ionic compounds poor conductors as solids?
no moving/free electrons
Why are ionic compounds good conductors as liquids?
Conducts electricity as liquid (charged ions free to move)
When is a covalent bond formed?
when atoms share a pair of electrons
What is an covalent bond between?
Non-metals + Non-metals
What are molecules?
a group of atoms held together by COVALENT bonds
What are 3 properties of covalent compounds?
Low fixed points
Do not conduct electricity
Insoluble in water, but dissolve in organic solvents
Why don’t covalent compounds conduct electricity?
atoms not charged
Why do covalent compounds have low fixed points?
the weak intermolecular attractive forces
