The Atomic Model

Flashcards about the atomic model

What is the atomic theory?

The theory that ALL matter is made up of atoms

Define subatomic particle.

A particle that is smaller than an atom

What are the key points of Dalton's atomic theory?

All matter is composed of atoms, which are indivisible and indestructible. All atoms of a given element are identical in mass and properties. Atoms of different elements have different masses and properties. Atoms combine in simple, whole-number ratios to form compounds. Atoms are rearranged in chemical reactions, but they are not creat

Why was Dalton's theory important?

Dalton's work was based on experiments and quantitative measurements, making it the first scientific atomic theory. Before Dalton, the idea of atoms had been proposed by ancient Greek philosophers, but it was more philosophical.

Describe Rutherford's Gold Foil Experiment.

Rutherford fired a beam of alpha particles at a thin gold foil and observed their deflection to study the structure of the atom.

What were the expected results of Rutherford's experiment based on Thomson’s Plum Pudding Model?

Alpha particles would pass straight through with very little deflection because the positive charge was thought to be spread out evenly.

What were the actual observations from Rutherford's experiment?

Most alpha particles passed straight through, some were deflected at small angles, and a few were deflected back almost directly.

What conclusions did Rutherford draw from his experiment?

Most of the atom is empty space. There is a small, dense, positively charged core (nucleus) in the center. The nucleus contains most of the atom’s mass. Electrons move around the nucleus in the empty space.

What is the significance of Rutherford’s model?

Rutherford disproved the plum pudding model and proposed the nuclear model of the atom: a tiny, dense nucleus surrounded by electrons in mostly empty space.

Why do atoms have mass?

Atoms have mass because they are made of protons, neutrons, and electrons, and protons and neutrons have mass.

Which subatomic particles contribute most to an atom's mass?

Protons and neutrons, which are in the nucleus.

What is relative measurement?

Measuring something by comparing it with something else.

What is the mass number of an atom?

The total number of protons and neutrons in the nucleus.

Why aren't electrons included in the mass number?

Because they are so light in comparison to the particles in the nucleus.

What determines the name of an atom?

The number of protons in the atom.

How are elements arranged in the periodic table?

According to the number of protons in their atoms.

What are the vertical columns in the periodic table called, and what do they represent?

Groups, which consist of elements that behave in similar chemical ways.

What are the horizontal rows in the periodic table called?

Periods