Chemistry Flashcards
Nucleus
The positively charged center of the atom consisting of protons and neutrons. Contains most of the atom’s mass. It is the control centre of the cell.
Electron
A particle that has a negative charge of electricity and travels around the nucleus of an atom.
Neutron
Have approximately the same mass as protons. They have no charge but contribute to the mass of the atom. 1800x heavier than electrons
Atom
The smallest part that a substance can be broken down into ‘naturally’.
Nucleus size
6 micrometers (µm)
Proton relative mass
1
Electron relative mass
0.0005
Neutron relative mass
1
How does the charge of subatomic particles result in an atom being neutral in charge.
All atoms have the same number of electrons as protons, so the positive and negative charges “cancel out”, making atoms electrically neutral.
Elements
The building blocks of all substances. Made up of atoms with the same number of protons in the nucleus
- same chemical properties
- proton number determines the element
Molecule
Two or more atoms chemically joined together. The number varies from substance to substance. If more than one type of element is bonded, we call it a compound.
Chemical bonds form because
Atoms like to have full valence shells (to become stable). They achieve this by sharing or transferring their electrons.
Types of bonds
Ionis: metal, nonmetal. Covalent: two nonmetals. Metallic: two metals.
Cation
Loss of electrons (positive charge).
Anion
Gain of electrons (negative charge).
Ion
At atom or molecule with an electric charge.
Law of conservation of mass
Mass cannot be formed nor destroyed.
Physical change
Changes in the appearance of a substance that are reversible and do not produce a new substance.
Chemical change
A change of materials into another, new materials with different properties and one or more than one new substances are formed.
Examples of physical change
Melting, boiling, breaking, dissolving.
Signs of a chemical change (observations)
Bubbles, cloudiness, temperature change, colour change, change in smell, precipitate (formation of a solid)
Examples of chemical change
Burning, rusting, decomposing.
Chemical properties
Combustibility, ability to burn (flammability), reactivity, acidity, toxicity, instability.
Physical properties
Appearance, melting and boiling points, density, solubility, polarity.