Y9 Science Chemistry Exam (10 minute revision (son))
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35 Terms
Which scientist discovered the electron?
J.J. Thomson
What did Rutherford’s gold foil experiment reveal?
The atom is mostly empty space with a tiny, dense, positively charged nucleus.
Name the three subatomic particles found in an atom.
Protons, Neutrons, Electrons
Which particle has a negative charge?
Electron
Which particle is in the nucleus and has no charge?
Neutron
What is the atomic number of an element?
The number of protons in the nucleus.
What does the mass number represent?
The total number of protons and neutrons.
An atom has atomic number 8 and mass number 16. How many neutrons?
8 neutrons (16 - 8 = 8)
Write the electron configuration of oxygen.
1s² 2s² 2p⁴
Write the electron configuration of sodium.
1s² 2s² 2p⁶ 3s¹
What is a valence electron?
An electron in the outermost shell of an atom.
How many valence electrons does lithium have?
1
What is a period in the periodic table?
A horizontal row; elements have the same number of electron shells.
What is a group in the periodic table?
A vertical column; elements have the same number of valence electrons.
Where are metals located on the periodic table?
On the left side and in the center.
Where are non-metals located on the periodic table?
On the far right side (plus Hydrogen).
List two properties of metals.
Good conductors of heat/electricity; malleable and ductile.
What is a metalloid?
An element with properties between metals and non-metals.
How does atomic radius change across a period?
It decreases (atoms get smaller).
How does atomic radius change down a group?
It increases (atoms get larger).
What is radioactive decay?
The process of an unstable nucleus losing energy to become stable.
Why is radioactive decay described as spontaneous?
It happens randomly and is not influenced by external factors like temperature.
What is emitted during alpha decay?
An alpha particle (2 protons + 2 neutrons / Helium nucleus).
What happens to the atomic number during alpha decay?
It decreases by 2.
What is emitted during beta decay?
A beta particle (high-speed electron).
Which type of radiation travels the furthest distance?
Gamma radiation
Which type of radiation can be stopped by paper?
Alpha radiation
What is an isotope?
Atoms of the same element with different numbers of neutrons.
How are isotopes of the same element similar?
They have the same number of protons and chemical properties.
How are isotopes of the same element different?
They have different numbers of neutrons and different mass numbers.
Why do elements in the same group have similar chemical properties?
They have the same number of valence electrons.
What is the electron configuration of magnesium?
1s² 2s² 2p⁶ 3s²
How many protons does an atom with atomic number 12 have?
12 protons
How many electrons does a neutral atom have?
The same number as protons (atomic number).
List two uses of radiation.
Medical radiotherapy, sterilizing equipment, carbon dating, nuclear power.