Atomic Structure / Dalton’s Theory / Matter & Mixtures

What were the postulates of Dalton’s atomic theory?

1. All matter is made of atoms; 2. Atoms of an element are identical; 3. Atoms cannot be created or destroyed; 4. Atoms combine in simple whole-number ratios; 5. In reactions, atoms are rearranged

How do we apply Dalton’s atomic theory?

To explain chemical reactions, predict ratios of elements in compounds, and understand atomic behavior

What did we deduce from Dalton’s atomic theory?

Atoms combine in whole-number ratios, matter is conserved, and compounds have definite composition

What is an isotope?

Atoms of the same element with different numbers of neutrons

What is the mass number?

Protons + Neutrons

What is the atomic number?

Number of protons

What is the charge of a neutron?

0

What is the charge of a proton?

+1

What is the charge of an electron?

−1

True or false: mass of neutron ≈ mass of proton

True

What is a cation?

Positively charged ion

What is an anion?

Negatively charged ion

What is an ion?

Atom or molecule with net electric charge

What determines the charge of an atom?

Number of protons vs. electrons

What is a covalent bond?

Sharing of electrons between atoms

What is an ionic bond?

Transfer of electrons between atoms

What is a pure substance?

Matter that has a uniform and definite composition

What is an element?

A substance that cannot be broken down into simpler substances

How many elements are there?

118

What are compounds?

Substances composed of two or more elements chemically combined

What is a heterogeneous mixture?

Mixture with visibly different components

Give an example of a heterogeneous mixture

Salad, sand and water

What is a homogeneous mixture?

Mixture with uniform composition throughout

Give an example of a homogeneous mixture

Saltwater

What is the macroscopic domain?

The world visible to the naked eye

What is the microscopic domain?

The world visible only through microscopes

What is the symbolic domain?

Uses symbols, formulas, or models to represent atoms, molecules, and compounds

What is the conservation of mass?

Mass cannot be created or destroyed in a chemical reaction