---
title: "Lawrencium (Lr): Atomic Mass, Electron Configuration & Properties"
url: https://www.moldraw.com/elements/lawrencium.html
description: "Lawrencium (Lr), element 103: atomic mass [266], electron configuration [Rn] 5f¹⁴ 7s² 7p¹, group 3, period 7, d-block actinide. Melting and boiling point, density, electronegativity and shells."
lang: en
publisher: Scidart Academy
generated: 2026-11-03
---
103Lr[266]

# Lawrencium (Lr) – element 103

Lawrencium is a chemical element with the symbol **Lr** and atomic number **103**. It is a actinide in group 3 (actinides), period 7 of the periodic table (d-block), and is a solid at room temperature.

Lawrencium (Lr) has atomic number 103, atomic mass [266] and electron configuration [Rn] 5f14 7s2 7p1.

[Download periodic table PDF](https://www.moldraw.com/printables/periodic-table.pdf)[Open interactive periodic table](https://www.moldraw.com/tools/free-chem-tools/interactive-periodic-table.html)

## Lawrencium facts

| Symbol | Lr |
| --- | --- |
| Atomic number | 103 |
| Atomic mass | [266] |
| Category | actinide |
| Group | group 3 (actinides) |
| Period | 7 |
| Block | d-block |
| Phase at 20 °C | Solid |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14 7p1 |
| Noble-gas notation | [Rn] 5f14 7s2 7p1 |
| Electrons per shell | 2, 8, 18, 32, 32, 8, 3 |

## Bohr model and shells

Lawrencium has 103 electrons in 7 shells: 2, 8, 18, 32, 32, 8, 3. Full configuration and noble-gas notation are in the table; work out any element or ion with the [electron configuration calculator](https://www.moldraw.com/tools/free-chem-tools/electron-configuration-calculator.html).

## Physical and atomic properties

| Melting point | 1900 K (1626.8 °C) |
| --- | --- |
| Electronegativity (Pauling) | 1.3 |
| Electron affinity | -30.04 kJ/mol |
| Ionization energies | 470 kJ/mol (1st) |
| Discovered by | Lawrence Berkeley National Laboratory |

Use the atomic mass in the [molar mass calculator](https://www.moldraw.com/tools/free-chem-tools/molar-mass-calculator.html) for any formula containing Lr.

## Position in the periodic table

Tap any element to open its page.

## Frequently asked questions

### What is the atomic mass of lawrencium?

The atomic mass of lawrencium is [266] (mass number of its longest-lived isotope, since it has no stable isotope).

### What is the electron configuration of lawrencium?

Lawrencium has 103 electrons: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 7p¹, or [Rn] 5f¹⁴ 7s² 7p¹ in noble-gas notation. Electrons per shell: 2, 8, 18, 32, 32, 8, 3.

### Is lawrencium a metal?

Yes. Lawrencium is a actinide.

### Where is lawrencium on the periodic table?

Lawrencium is in group 3 (actinides), period 7, in the d-block.

Data: [Periodic-Table-JSON](https://github.com/Bowserinator/Periodic-Table-JSON) (CC BY-SA 3.0); standard atomic weights from IUPAC (abridged). Values in brackets are the mass number of the longest-lived isotope.