End of Term 2 Test Flashcards
What is an Isotope
Atoms of an element that have the same number of protons but a different number of neutrons in the nucleus.
For example, carbon atoms have 6 neutrons in their nucleus, but some have 7 and some have 8
Radioactive decay of isotopes
Some isotopes become unstable when the ratio of neutrons to protons is too high,
they may undergo radioactive decay to become more stable.
There are 3 types of radioactive or nuclear decay: Alpha Decay, Beta Decay, Gamma radiation
Alpha Decay
Symbol: a
Nucleus ejects an alpha particle (contains 2 neutrons and 2 protons – similar to a helium atom), occurs in an atom with very heavy nuclei
- Can be stopped/penetrated by a piece of paper
Uses: Many smoke detectors contain americium-241, which releases alpha radiation and helps detect smoke.
Penetration power: Low energy
Beta Decay
Symbol: B
Nucleus ejects a beta particle (1 electron)
- Can be stopped/penetrated by aluminium foil
Uses: Beta-radiation emitters can be used as cancer treatment
Penetration power: High energy
Gamma radiation
Symbol: Y High energy electromagnetic rays released from the nucleus - Can be stopped/penetrated by lead Uses: sterilise medical equipment Penetration power: High energy
Electron shell diagrams
2 electrons in the first shell
8 in the second shell
up to calcium 8, above calcium 18 in the third shell
32 in the fourth shell
Protons
Positively Charged (+1), In the nucleus, relative mass 1
Neutrons
Neutral, In the nucleus, relative mass 1
Electrons
Negatively Charged, Around the nucleus, 1/1840
What does a PH scale/ Universal indicator do?
A scale that measures the acidity to find an acid or a base
What colour does litmus paper become when met with an acidic solution
Red
What colour does litmus paper become when met with a base solution
Blue
Between what rating are Bases on the Ph scale
8-14
Between what ratings are Acids on the Ph scale
0-6
What rating is neutral on the Ph scale
7
Bases
Taste bitter, feel slippery and soapy, if they dissolve in water it is alkalis (base)
Acids
- Taste sour, produce a prickling or burning sensation if come in contact with your
skin, all contain at least one hydrogen atom and tend to react with many metals - Can be strong or weak. Concentrated acids can burn you and would show lower on the pH scale while weaker acids you can eat and drink like an orange and would show more neutral
Atomic number
The number that represents the total number of protons in the atomic nucleus
Mass number
The number that represents the total number of protons and neutrons in the atomic nucleus
Atomic Theory: Dalton
All matter is made of atoms. Atoms are indivisible and indestructible. All atoms of a given element are identical in mass and properties. Compounds are formed by a combination of two different atoms.
Atomic Theory: Thompson
His research in Cathode rays led to the discovery of an electron. He pursued further investigations into atomic structure. He also discovered the isotope and the subatomic particle. This is the plum pudding model
Atomic Theory: Rutherford
The Rutherford model was used to describe an atom. He overturned Thompsonʼs theory and found an atom has a tiny and heavy nucleus. He found major portion of the atom is empty, the centre is called the nucleus and the positively charged particles are found in the nucleus
Acid + Base (Neutralisation) Reaction:
Acid + Base -> Salt + Water
When an acid and a base combine, they will react in which is called a neutralisation reaction. This creates a new product and creates a new pH. The product will change depending on the base.
E.g. Magnesium hydroxide + Hydrochloric acid ̶> Magnesium chloride + water
= MgHO + HCl ̶> MgCl + H2O
Acid + Carbonate Reaction
Acid + Carbonate -> Salt + Water + Carbon dioxide
Carbonates release carbon dioxide which can be seen as bubbling. Water and Carbon dioxide are formed because the carbonate ions react with the H+ ions from the acid
E.g. Nitric acid + Copper Carbonate -> Copper nitrate + salt + carbon dioxide
Salt
compound that contains a metal (positive) ion and a non-metal (negative) ion
E.g. Potassium chloride is the salt produced when hydrochloric acid reacts with potassium hydroxide.
Acid + (Reactive) Metal Reaction:
Acid + Metal -> Salt + Hydrogen
When acids react with metals they produce hydrogen gas and a salt. The salt that forms in the combination of the positive metal ion from the base and the negative non-metal ion from the acid.
E.g. Hydrochloric acid + Magnesium -> Magnesium chloride + Hydrogen
Identify the salts produced in common acids
- Hydrochloric acid (HCI) produces chloride salts
- Nitric acid (HNO3) produces nitrate salts
- Sulfuric Acid (H2SO4) produces sulfate salts
Describe the tests for Carbon dioxide and Hydrogen gas
Carbon dioxide: Lime water test or extinguishes a lit paper
Hydrogen gas: Pop test
The current accepted model of an atom
- Nucleus consists of protons and neutrons
- Protons are positively charged particles
- Neutrons have no charge
- The mass of an atom is mostly because of the mass of the nucleus
- Electrons (negatively charged particles) move around the space around the nucleus
- Overall, atoms are neutral (have no charge) because there is always the same number of positive and negative electrons in any atom
