chemistry unit 1 study guide ionic pt 1

Thompson's Plum Pudding Model

A model of the atom proposed by J.J. Thomson, describing a positive sphere with negative electrons embedded throughout, like plums in a pudding. It had no nucleus.

Density (d)

The mass (m) of a substance per unit volume (V). Formula: d = \frac{m}{V}

Water Displacement Method

A technique used to find the volume of an irregular object by submerging it in water and measuring the change in water level. Formula: Volume_{object} = Final\ Level - Initial\ Level

Physical Change

A change in the form or state of a substance, but its chemical composition stays the same.

Chemical Change

A process where a new substance with a new chemical composition is formed.

Evidence of a Physical Change

Examples include ice melting to water, salt dissolving in water, or cutting paper.

Evidence of a Chemical Change

Examples include a banana rotting, baking soda reacting with vinegar, or burning wood.

Test for Chemical Property

Seeing if a substance reacts with an acid (i.e., producing gas like H_2).

Nonpolar Covalent Compound: Diphosphorus pentaoxide (P2O5)

A compound formed between two phosphorus atoms and five oxygen atoms, exhibiting nonpolar characteristics.

Ionic Compound: Iron(III) hydroxide (Fe(OH)_3)

An ionic compound formed between the iron(III) ion (Fe^{3+}) and three hydroxide ions (OH^-).

Polar Covalent Compound: Carbon tetrafluoride (CF_4)

A compound consisting of a carbon atom covalently bonded to four fluorine atoms. While the C-F bonds are polar, due to its symmetrical tetrahedral geometry, the CF_4 molecule is nonpolar overall.

Properties of Ionic Compounds

High melting point, hard/brittle.