Atoms and Elements Ch 1-4 Pearson
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materials (d)
substances used to make objects.
2 types of materials are
pure substances (elements and compounds) or mixtures
Materials with distinct and measurable properties like melting points or density
pure substances
Materials that have variable properties depending on the relative amounts of substances present
mixture
Melting point and boiling point, density, hardness are all ________ properties.
physical
Two types of pure substances
elements and compounds
Compound
two or more elements chemically combined
Chemical formula
shows the elements present in a compound and the ratio between them
Separation techniques use __________ properties of substances to separate them
physical
Separation techniques use these physical properties 5
particle size, solubility, density, magnetism and boiling point
Nanoparticles
particles that are 1-100 nm in diameter.
Nanometre
1 x 10 -9 metres
Is wood a material? Why?
Yes. It is used to make other objects like houses.
Is carbon dioxide a material? Why?
No. No objects are made of carbon dioxide.
Elements
sustance made up of one type of atom. Atoms are the same type if they have the same number of protons. Neutrons and electrons may differ.
Atom 1 has 6 protons and 6 neutrons. Atom 2 has 6 protons and 7 neutrons. Are they the same type of atom?
Yes. They have the same number of protons
Atom 1 has 6 protons and 6 neutrons Atom 2 has 5 protons and 6 neutrons. Are they the same type of atom?
No. They have different number of protons.
Can you change the melting point of an element?
No
Can you change the melting point of a compound?
No
Can you change the melting point of a mixture
Yes -change the ratio of components
Metal
a substance with high electrical and thermal conductivity and lustre ( reflects light when freshly prepared). Also ususally malleable and ductile
Metals found pure on Earth
gold, silver copper
alloy
a mixture of a metal and other metals or carbon
Steel is an alloy of what two main elements?
iron and carbon