Keshu

Burning releases exothermic reaction

An exothermic reaction is a chemical or physical process that releases energy, typically as heat, light, or sound, into its surroundings.

A chemical bond is the attractive force that holds atoms, ions, or molecules together to form a compound.

An attractive force is a force that causes objects or particles to move toward each other.

Combustion is a rapid chemical reaction between a substance, called a fuel, and an oxidant, usually oxygen, that releases energy as heat and light, often with a flame.

An oxidant, also called an oxidizing agent, is a chemical substance that accepts electrons from another substance during a chemical reaction.

Group 7- the halogens

fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).

The melting point of the halogens top to bottom decreases because as you move down, the atoms get larger and heavier, leading to stronger van der Waals force between the diatomic molecules, requiring more energy to melt or boil.

Van der Waals forces are weak, short-range electrostatic attractions between neutral atoms or molecules.

Electrostatic attraction is the force of attraction between two oppositely charged particles, like a positive and a negative charge.

The four fundamental forces are gravity, the electromagnetic force, the strong nuclear force, and the weak nuclear force.

What are atoms like

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Atoms are made up of three kinds of particles: protons, neutrons, electrons.

These particles are arranged in a similar way in every atom

The protons and neutrons are tightly packed in the center. There they form the nucleus of the atom.

The electrons orbit the nucleus around it.

Dispersal

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Seeds contain embryo plants. When they start to grow, each plant need water, light and mineral salts in order to grow well.

If all the seeds just fell of the plant onto the ground, they would all be trying too grow in the same place. The new little plants would all compete with each other for water, light and mineral salts. They would also have to compete with the parent plant, too.

The new plants have a better chance of growing if they are in a different place. They need to be dispersed away from the parent plant and others

if seedlings (young plants) grow next to there parent plant they may not get enough water, light or mineral salts to grow well.