Atoms, elements and compounds Flashcards
There are over __ different elements, which are made up of atoms.
100
___ are used to help explain elements, compounds and mixtures.
Particle diagrams
Some elements exist as individual __, but some bond together to form __ of the same element.
atoms
molecules of atoms
Why could the iron be separated easily from the sulfur before they were heated together, but not afterwards?
Iron is a magnetic element, so it can be separated from a mixture using a magnet. But after the iron and sulfur have been heated, they react to make the compound iron sulfide. You cannot easily separate an element from a compound.
An element is a pure substance that cannot be broken down into any other ___.
substances
An element is made from just one type of __
atom
Some elements exist as individual ___, but some exist as.
atoms
molecules
Most of the elements are ___.
metals
How many chemical elements do you think there are?
there are actually 118 chemical elements
The air we breathe is mostly made from __ and __
nitrogen
oxygen
In the periodic table metals are found on the __
left
In the periodic table non_metals are found on the __
right
Describe properties ofr Hydrogen
It is an explosive gas which burns with a very clear ‘squeaky pop’ when a burning splint is inserted into a test tube containing it.
Helium is also a gas, but is very different from hydrogen because it doesn’t take part in any ___
chemical reactions.
Scientists Marie and Pierre Curie discovered two elements: __ and __ . For these discoveries, Marie Curie received a .
radium
polonium
Nobel prize
___ can be used to show the atoms of elements. All of the atoms in a particle diagram must be the same __ and__ .
Particle diagrams
colour
size
In a solid element the particles are ___ and arranged in a ___
close together
regular way
In a liquid element the particles are ___ and arranged in a ___
close together
random way
In a gaseous element the particles are ___ and arranged in a ___
apart
random way
Some non-metal elements are made from atoms which are bonded into clusters called ____.
molecules
A ___ is a pure substance that is made from more than one element. In a __ , elements are chemically bonded together, which makes it very difficult to separate them.
compound
compound
When a compound is made, the atoms of the elements bond together in a fixed ___ . This means that each compound can be represented by a
ratio
chemical formula.
the formula of water is __
H₂O
the formula of carbon dioxide is __
CO₂.
To break apart the elements in a compound, a ___ must take place.
chemical reaction
What is electrolysis?
Splitting up a liquid or dissolved compound into its elements using electricity.
What is thermal decomposition?
Breaking down a compound into its elements, or simpler compounds using a high temperature.
When elements make a compound through a physical process such as ___ or ___ , it is impossible to separate them.
filtration
boiling
A particle diagram for a compound will show more than one type of __
atom
Water molecules are made up of __ elements -___ and__ .
two
hydrogen
oxygen
Carbon dioxide molecules are made up of __ elements - __ and __.
two
carbon
oxygen
Compounds made from non-metal elements that are bonded together usually form __.
molecules
Compounds including both a __ element and a __ element bonded together do not form molecules.
metal
non-metal
Compounds including both a metal element and a non-metal element bonded together form a ___
lattice
A ___ is formed when two or more elements or compounds are present without being chemically bonded together.
mixture
Substances which have been mixed are not present in specific ___ or __ like they are in a compound
amounts
ratios
In a mixture, the two ingredients can be separated using ___ , without chemical reactions.
physical processes
A mixture of sand and water can be separated using ___
filtration
A solution of salt and water can be separated using __ or ___
crystallisation
distillation
A mixture of iron filings and sulfur powder can be separated using a ___ .
magnet
Air is a mixture which is made mainly of ___ molecules and ___ molecules.
nitrogen
oxygen
Whereabouts on the periodic table are the non-metals found?
On the right.
Which technique is most likely to be used to separate the elements which are bonded together in a compound?
Thermal decomposition.
Thermal decomposition can be used to break down some compounds into elements. Simple techniques like filtration and evaporation will not work, but they can be used for separating mixtures.
Letters from the alphabet are used to represent chemical ___ .
elements
An element’s chemical symbol is a single ___ letter or a capital letter followed by a __ letter.
capital
lower case
The __ shows the chemical symbols for all the different elements.
periodic table
The formula H₂O is used to represent water. What does the formula mean?
The formula H₂O shows that water is made from two atoms of hydrogen (H) bonded to one atom of oxygen (O).
What is an element?
An element is a substance that cannot be broken down into any other substance. Every element is made up of its own type of atom.
Elements are represented by letters from the alphabet. These letters are also known as ___ .
symbols
The symbol H is for ___
hydrogen
The symbol C is for ___
carbon
The symbol He is for ___
helium
The symbol Mg is for ___
magnesium
The symbol Na is for ___
sodium
A lot of the element names have come from Latin. The Latin name for sodium was ‘___’.
natrium
Which element has the symbol N?
Nitrogen.
There are 118 chemical elements and they are listed on the periodic table.
___ chemical elements occur naturally on Earth and in the universe.
elements are made using nuclear reactions.
94
24
The formula of a compound shows how many __ of each element are bonded together.
atoms
The formula is made up of ___ and.
symbols
numbers
Water is a compound of hydrogen and oxygen. The symbols H for hydrogen and O for oxygen are used to represent .
H₂O
Oxygen gas is a molecule made of two oxygen (O) atoms represented as .
O₂
Sulfuric acid is a combination of hydrogen (H), sulfur (S) and oxygen (O) represented as
H₂SO₄.
For compounds made from metals and non-metals, the ratio is simplified down as much as possible.
The formula for Natrium Choldire is __ instead of Na₈Cl₈.
NaCl
Calcium chloride has the formula CaCl₂, so there are __ as many chlorine atoms present as calcium atoms.
twice
Many non-metal elements are made from molecules, and these have a chemical formula which shows how many __ are bonded to each other in their molecules.
atoms
Which elements does MgCl₂ contain? How many of each type of atom are present?
MgCl₂ is the formula for magnesium chloride, which is a compound containing magnesium (Mg) and chlorine (Cl). There are two atoms of chlorine for every one atom of magnesium.
Carbon exists in different forms, including __ , ___ and __ .
graphite
diamond
graphene
Carbon atoms are arranged in a regular pattern, meaning carbon is __ at room temperature.
solid
Nitrogen makes up about __ of the Earth’s atmosphere.
78% o
Nitrogen isn’t very reactive, but it can react with oxygen at high temperatures, such as in car engines. These reactions make __ .
nitrogen oxides
The boiling point of nitrogen is __ , so liquid nitrogen is very cold indeed. This means liquid nitrogen is ideal for freezing food, such as vegetables, very quickly, allowing them to stay fresher for longer.
−196 °C
