Yes, they do.
John Newlands.
The number of protons in an atom of an element.
Using the formula: ((isotope 1 mass x abundance) + (isotope 2 mass x abundance)) ÷ 100.
The lowest available energy levels (shells closest to the nucleus).
Compounds contain two or more elements chemically combined in fixed proportions and can be represented by formulae.
Discovery of electrons, protons, neutrons, and knowledge of isotopes.
It concluded that the mass of an atom is concentrated at the center (nucleus) and that the nucleus is charged.
0, meaning the number of protons equals the number of electrons.
The same amount of electrons in their outer shell, leading to similar chemical properties.
How many electrons are in each shell.
A bright yellow flame.
It ignites with sparks and a lilac flame, disappearing very quickly.
Chlorine will displace bromine, forming potassium chloride and bromine.
They have ions with many different charges, form coloured compounds, and are useful as catalysts.
An average value that accounts for the abundance of the isotopes of the element.
Compounds can only be separated into elements by chemical reactions.
A lilac flame.
They react with metals.
Transition elements have higher melting points (except for mercury).
12.4.
2 electrons.
Having a single electron in their outer shell and reacting vigorously with water.
Reactivity decreases.
Carbon-14 and carbon-12.
In order of atomic (proton) number and by similar properties in columns known as groups.
Compounds are formed from elements by chemical reactions, which involve the formation of new substances and often an energy change.
It fizzes steadily and gradually disappears, producing a white powder that settles on the sides of the container.
To the left and towards the bottom.
He suggested that electrons orbit the nucleus at specific distances, supported by experimental data.
Smaller particles called protons, each having the same amount of positive charge.
About 0.1 nm.
+2, +3, +4, +5, +6.
The Haber process involves nitrogen and hydrogen to produce ammonia, and transition metals are used as catalysts.
Copper.
Reactivity increases going down the group.
James Chadwick.
Transition elements are much less reactive and do not react as vigorously with oxygen or water.
Atoms of the same element with different numbers of neutrons.
A strongly red-tinged flame.
8 electrons.
They have 8 electrons in their outer shell (except helium, which has 2).
+1.
Atoms make up all substances and are the smallest part of an element that can exist.
Decomposition of hydrogen peroxide.
They form coloured compounds.
1 electron.
They increase with increasing relative atomic mass.
20%.
The sum of the protons and neutrons in an atom.
Because similar properties occur at regular intervals.
Atoms were initially thought to be tiny spheres that could not be divided.
-1 charge.
Transition elements are harder and stronger than group 1 elements.
2, 8, 1.
Mixtures can be separated by physical processes such as filtration, crystallisation, simple distillation, fractional distillation, and chromatography.
Some alpha particles emerged at different angles, and some were deflected back, indicating a small concentration of positive charge in the atom.
80%.
Chemical symbols represent an atom of an element, e.g., Na represents an atom of sodium.
Similar properties occur every eighth element.
A mixture consists of two or more elements or compounds not chemically combined together, with unchanged chemical properties.
It led to the plum pudding model, where the atom is a ball of positive charge with negative electrons embedded in it.
Dmitri Mendeleev.
It fizzes rapidly, melts into a ball, and disappears quickly.
They have a stable arrangement of electrons with full outer shells.
