Elements, compounds and mixtures Flashcards
(20 cards)
What were the earliest scientists called?
Alchemists
How many natural elements are there?
92
How many artificial elements are there?
24
What are the dangerous elements?
Sodium, potassium and mercury
How do you determine the neutrons in an atom?
Neutrons = mass no. - atomic no.
How many electrons does the first shell hold?
2
How many can the 2nd and 3rd shell have? And how are they grouped?
8 maximum and they are grouped two together
What are compounds?
Substance made up of two or more different types of atoms that have been bonded together.
What is a mixture?
A combination of substances in which each keeps their own properties.
What are protons?
Tiny
Heavy
Found in nucleus
Have a positive electrical charge
What are electrons?
Very light
Negatively charged particles
Inside atom but circles the nucleus
How do you determine the protons and electrons?
Protons and electrons = mass no.
What are neutrons?
Tiny
Heavy
No electrical charge
Inside nucleus
How do you separate a compound?
Passing electricity through it
Burning the compound
Mixing the compound
What are the features of metals?
- solid at room temp
- can be polished
- good conductors of electricity and heat
- malleable
- ductile
- melts at high temps
What are features of non-metals?
- they cannot be polished
- brittle
- not malleable or ductile
- poor conductors of heat and electricity
- melt at low temps
What are metalloids?
Are elements that have features of both metals and non-metals
Examples of metalloids
Boron
Silicon
Arsenic
How many elements are non metal?
22
What are the first 20 elements in the periodic table? and their signs?
hydrogen- H helium- He lithium- Li beryllium- Be boron- B carbon- C nitrogen- N oxygen- O fluorine- F neon- Ne sodium- Na magnesium- Mg aluminium- Al silicon- Si phosphorus-P sulphur- S chlorine- Cl argon- Ar potassium- P calcium- Ca
