C1-Atomic Structure Flashcards

1
Q

What is an atom

A

Atoms are the smallest pieces of an element that can exist.

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2
Q

How many elements have been dicovered

A

118 and each has its own chemical symbol

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3
Q

What are compounds

A

Atoms of different elements can be combined together to create compounds. Compounds have formulae that are made by combing the chemical symbols of the elements that make them. Different combinations of atoms result in different compounds. A compound contains at least 2 different elements

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4
Q

What are the key features of a chemical reaction

A

Compounds are broken up or formed. At least 1 new substance is created. They have a measurable energy change. No atoms are created or destroyed.

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5
Q

What does a chemical equation show

A

Shows what is happening in a chemical reaction using symbols or words. The reactants (chemicals that are reacting) are on the left hand side, and the products (the chemicals that are forming) are on the right hand size

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6
Q

What are mixtures?

A

Mixtures are made of 2 or more substances (elements or compounds) that haven’t been chemically combined. Mixtures can be separated. Their chemical properties don’t change because they have been mixed with another substance. Mixtures are common, e.g air is a mixture of gases such as carbon dioxide and oxygen

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7
Q

Explain Chromotography

A

.Separates solutions with a number of different solutes (solids) in the solvent (liquid)

.Place a drop of the solution to be separated near the bottom of a piece of chromatography paper. Dip the very bottom of the paper into a suitable solvent. The solvent (liquid) moves up the paper and carries the solutes in the solution with it

.Different solutes move at different speeds so they separate on paper

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8
Q

Explain filtration

A

.Separates mixtures of insoluble solids and liquids
.Done by pouring the mixture through filter paper
-the insoluble solid is trapped
-the liquid runs through the paper and is collected below

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9
Q

Explain crystallisation

A

Separates solutions into their constituent (different )parts: disolved solids (solutes) and liquid (solvents).

.Heat the mixture so that the solvent evaporates. Eventually crystals ld the solute will form. We can collect the solvent by condensing it as it evaporates

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10
Q

Explain simple distillation

A

Separates 2 liquids with different different boiling points

.The mixture is heated until the liquid with the lower boiling part starts to boil. The vapour released passes through a condenser where the gas cools back into a liquid

. A thermometer is used to make sure the highest boiling is not exceeded otherwise both liquids would boil and the process would not separate them

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11
Q

Explain fractional distillation

A

Separates lots of liquids with different boiling points

The mixture is slowly heated until the liquid with the lowest boiling point boils and then condenses

Then the temperature is increased slowly to collect the other fractions through boiling and condensing

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12
Q

Explain Thomson’s plum pudding model

A

In 1897, an English physicist called J.J Thompson discovered electrons

He modelled the atom as a plum pudding with is a ball of positive charge dough with negatively charged electrons mixed in with the ‘dough’

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13
Q

Explain Rutherford’s nuclear model

A

.in 1909, Ernest Rutherford discovered that alpha particles could bounce back off atoms. He concluded that an atom’s mass is concentrated in the atom’s centre, this was called the “nucleus” and it contained positively charged particles called protons and negative electrons mixed in

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14
Q

Explain the modern model

A

Niels Bohr discovered that electrons orbit the nucleus at fixed distances
In 1932 James Chadwick discovered that some particles in the nucleus have no charge at all. He called them neutrons

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15
Q

What is the overall charge of an atom

A

Atoms have no overall charge as they cancel each other out

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16
Q

What are the relative charges of the three subatomic particles?

A

Protons +1
Electrons -1
Neutrons 0

17
Q

What are the relative masses of the sub-atomic particles?

A

Relative mass of protons and neutrons = 1

Relative mass of electrons= 0.0005
Which gets rounded to zero

18
Q

What is the size of an atom

A

Atoms have an average radius of about 0.1nm

The nucleus of an atom is 10,000 times smaller than the atom

19
Q

Atomic number and mass number

A

The mass number of an atom also called relative mass is the total number of protons and neutrons in a nucleus. The atomic number of an atom is the number of protons in the atom