Science Y8: 8F (Periodic Table) Chemistry

Dalton's atomic theory

All matter is made of tiny, indestructible atoms.

Atoms

Cannot be created or destroyed.

Element

Made of identical atoms.

Compound

Atoms joined in fixed ratios.

Chemical reactions

Atoms rearrange to form new substances.

Reactants

Substances before a chemical reaction.

Products

Substances formed from a chemical reaction.

Signs of a chemical reaction

Color change, gas production, solid formation, temperature change.

Word equation

Represents a chemical reaction using words.

Law of conservation of mass

Mass of reactants equals mass of products.

Physical change

No atoms lost or gained, mass stays the same.

Change of state

A physical change between solid, liquid, or gas.

Melting point

Temperature at which a solid becomes a liquid.

Boiling point

Temperature at which a liquid becomes a gas.

Element symbols

Agreed scientific shorthand for elements.

Formula

Represents the number and ratio of atoms in a substance.

Sodium chloride

Chemical formula: NaCl.

Metal properties

High melting points, strong, malleable, ductile, shiny, good conductors.

Non metal properties

Low melting points, brittle, dull, poor conductors.

Chemical properties

Describe how substances react, like flammability and acidity.

Physical properties

Describe appearance or behavior, like melting point and density.

Periodic table

Organizes elements by atomic number and properties.

Mendeleev

Originally arranged elements by mass.

Modern periodic table

Ordered by atomic number.

Groups

Vertical columns with similar properties.

Periods

Horizontal rows showing trends.

Alkali metals

React with water to form alkaline solutions and hydrogen gas.

Noble gases

Very unreactive elements.

Oxides

Formed when elements burn in oxygen.

Acid base reaction

Acid + metal oxide → salt + water.